Physics and Chemistry 3 Andalucía Sample book

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N O I T A C U D E Y R A D EC O N

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Building

Blocks

this is

your book

Reading and listening

ch unit

f ea The opening pages o

Speaking

5

We read and listen about the topic of the unit, learning about key concepts and developments in technology.

4

Nature of forces g

Reading and listenin

Geolocation

prevent non-communicable Our app is designed to diseases through exercise. you can do. different forms of exerciseany exercise The app will show you if you haven’t done It will send you a notification that day.

this, magnet. Due to like a gigantic to guide them for Our planet behaves able to use a compass of north with people have been nt indicates the direction centuries. This instrume navigation because it allowed night l for accuracy. It is essentia . sky was overcast journeys when the gy have made us in science and technolo took a qualitative y Today, advances the compass. Humanit satellites in orbit almost forget about when it placed artificial leap in geolocation around the Earth. gy was only positioning technolo satellite g, were In the beginnin geolocation devices to purposes and the , it is very easy used for military however ys, e. Nowada phones. bulky and expensiv into our mobile it is integrated used have a GPS since we have become to the Internet, receiving relevant Furthermore, thanks map, online an s on to to orienting ourselve sending our location surroundings and our on ion informat other people. text. tion’ as used in the definition of ‘geoloca 1 Choose the best location. identifying a specific a) The process of are using the Internet. shows where you that gy b) Technolo of the Earth. c) The position make around the Earth satellites in orbit 2 Why do artificial necessary? compasses no longer you have used the situations in which why Make a list of the 3 Use the list to explain of your mobile. y, in line necessar is satellite location le Internet access universal and affordab with the goal 9.c.

It’s time

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to exercise

Writing A short report report Prepare a small of “globalization.” enon.

5 Reflect on the meaningeveryday life you notice this phenom on

which parts of your

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Writing 120

The audios of each unit’s content are available at www.anayaeducacion.es

We speak about the different issues relating to the unit and the UN Sustainable Development Goals.

Speaking An advertisement a mobile Goal 3.4. Invent le Development ment Analyse Sustainab then create an advertise reach this goal application to help for it. groups. le • Step 1: Form small non-communicab treat or prevent the app will g.

• Step 2: Decide how health and well-bein it will promote mental how or diseases it provide the app. How will be the features of • Step 3: Decide options? Will there there be search accounts? Will it information? Will d to social media connecte be it notification? Will to the user? How? be personalized the app to the class.

• Step 4: Advertise

We write a variety of different styles and types of text relating to the unit topic, sometimes relating them to the UN Sustainable Development Goals. By practising different styles of writing, we improve our writing skills we need.

SDG. Reflection on and analysis of SDGs, such as gender equality, climate action, reducing inequalities, etc.

content development 2

ä 2.3 Nuclear power station

An energy transformation is produced in an electric power station: from primary energy (that which we find available in nature) to electrical energy.

Afterwards, this is distributed by means of the power lines of the country to the different points of consumption.

When we talk of nuclear power stations, we are referring to nuclear fission power stations, in which uranium is normally used. This deals with a non-renewable source of energy. Uranium is a radioactive material. Its atoms are not stable and end up splitting (undergoing fission) forming other lighter atoms. In the process of fission, matter disappears, transforming into energy which is invested to heat water. The steam is conducted through pipes until the turbines of the generator move, producing electricity, as seen in the lower image.

Therefore, the challenge of producing electrical energy involves looking for natural resources that could make the alternator turn. Several alternatives have been found to do this, and a type of electric power station stems from each one.

ä 2.2 Thermal power station Thermal power stations transform chemical energy, obtained from burning coal, oil or natural gas; and the energy released is invested in heating water until it boils. The steam is conducted through pipes to the turbines of the generator, connected to the alternator.

When the steam at high pressures moves the turbines, these make the alternator turn and electrical energy is produced which travels through power lines, as seen in the image below.

This source of energy is non-renewable; coal and oil will end up being exhausted, and they cannot be regenerated as they need millions of years to do so. It is also pollutes, as the waste substances are released into the atmosphere. Carbon dioxide stands out among them, as it contributes to the rise in the greenhouse effect, and therefore to global warming.

In the image below, why do you think the smoke from the chimney is dark while that from the cooling tower is white?

Nuclear changes are very profitable from an energy perspective; with 1 g of uranium the same energy can be obtained as with 2 000 kg of oil, or around 3 000 kg of coal.

One disadvantage of these power stations is that they produce radioactive waste, which must be kept carefully isolated as long as they are toxic to Matter is condensed energy. The amount of energy E that forms a piece of matter life. But the main risk is their enormous danger in the face of accidents. of mass m is determined by Einstein’s If something goes wrong it can cause a radioactive leak, such as what equation, E = m · c 2 where c is the speed happened in Chernobyl in 1986, with hundreds of thousands of people light,forces (c = 3 affect · 108 m/s).

Now, that you knowofhow bodies (deformations and changes seriously affected and thousands of square kilometres of land abandoned in motion), you will notice forces acting all around you in everyday life. for decades until the radioactive contamination fell to tolerable levels.

Also, more recently, in Fukushima in 2011, although in this case, despite What similarities and differences the seriousness of the accident, there were less consequences. ä 3.1 Weight do you see between a thermal

3

EVERYDAY FORCES

In other words, weight is the force that makes bodies fall. Experiments Transmission show that weight is directly proportional line to mass. In mathematical terms:

Containment structure

Cooling tower

Steam generator

Steam

Transmission line

Condenser

166

Turbines

Advantages and disadvantages. Write a list of factors in favour of and against thermal power stations.

Carry out the same task with nuclear fission power stations.

4

Why do we not take advantage of gyms where people pedal on exercise bikes to make an alternator move? Think about this idea and write if it would be possible to carry it out.

Generator

Alternator

We also know that when we drop a body, it falls vertically. This tells us that weight is a force that points vertically downward (lower left picture). It is the force the Earth exerts on every Transformer single body, expressed in newtons in the SI.

3

Fuel

The steam moves the turbines of the generator. The electricity produced is transformed to the desired voltage

Transformer

to transport it via the high-tension lines. The cooling tower, together with the condenser, cools the water.

Find a resource on the production of electrical energy on anayaeducacion.es.

In everyday life, people measure their weight in kilograms. However, kilograms actually measure mass, not weight.

Generator

Understand, think, search…

Turbines

P=m·g

In this equation, gravity, g, is the constant of proportionality. On the Earth’s surface, gravity = 9.8 m/s2.

Condenser

Control rods

Water

Steam

Water

Reactor

Cooling tower

Boiler

power fall, station a increases nuclear during the fall. This We know that when bodies their and speed fission power station? tells us that a force is acting on them: weight, W.

Nuclear fission power station

Thermal power station

Working with pictures

As mentioned in a previous unit, this energy transformation is possible thanks to the alternator. From an energy perspective, what is done is transform mechanical energy (that of the turning of the alternator) into electrical energy.

Working with pictures

Understand, think, search…

Activities to strengthen learning and relate knowledge. res. with pictu Working city a p your ca Develop and n o rvati for obse . n tio interpreta

The problems solved allow the learning of reasoning processes and problem-solving strategies.

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Energy that forms matter

ä 2.1 Production of electrical energy

Working with pictures

Two types of activities:

Unit

ELECTRICAL POWER STATIONS

An apple falls to the ground and remains stationary. In your notebook, draw a diagram to show the forces exerted on the apple.

Look at the upper right picture. It shows a body hanging from a string, yet it doesn’t fall. The string holding the body exerts an opposite force, which cancels out the weight. This force is called tension.

5 The calorific value of coal depends on the type of coal.

Put aLet’s book on the ground. it doesn’t move, it is in equilibrium. imagine a type that Since gives off 30 000 kJ for each We kilogram know that is Determine acting onhow it, but does thatweight it burns. manythis grams of not make the bookmatter accelerate This tells us there is another force acting would downwards. have to disintegrate in order to obtain the on the book thatofcancels same amount energy. out weight. This force is called the normal force, N. 6 Look up information on how radioactive waste is The isolated normal force is the force that solid surfaces, like the ground, exert on from nuclear power stations. bodies supported on them. It is always perpendicular to the surface and prevents the object from passing through it (lower right picture).

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Weight and normal force

You already know about elastic force. In fact, there are many examples of it in our everyday lives.

The lower right picture shows what would happen if we hang a body from a spring instead of from string. The spring would extend when weight is attached to it because it is elastic and immediately would exert an elastic force to try to recover its original shape.

Problems solved 800 N/m. How far will the spring extend?

Fe

The weight of the bucket is cancelled out by the elastic force of the spring: We can also calculate this using the equation that describes the relationship between weight and mass: m P = m · g 8 N = kg · 2 s Therefore: m·g k · Dl = m · g 8 D l = k m 3 kg · 9.8 2 s . 0.037 m = 3.7 cm Dl = N 800 m

she exert on the floor when she stands still?

b) Determine his weight on Mars, considering that gravity on the red planet is 3.7 m/s2.

P

k = 4.5 N/cm, stretching it until it reaches 28.5 cm. a) Determine the mass of the hanging object.

b) How long will the spring stretch if we hang a 2 kg object on it?

28 When a 5 kg body is hanging from a 35 cm spring, it stretches until it reaches a length of 43 cm.

25 A wooden plank is used as a bridge to cross over a P3 P1 N1 = P 1

P2 N2 = P2

P

The elastic force of the spring in equilibrium also cancels out the weight of the suspended body.

27 An object is hanging from a 25 cm long spring with

24 A man weighs 850 N on Earth. a) What is this man’s mass?

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P

Tension is the opposite force exerted by string used to hold a body. It cancels out the weight force.

1 A 3 kg bucket hangs from a spring with an elastic constant of

23 Calculate the weight of a 50 kg girl. What force does N2

Acceleration produced by weight.

T

ä 3.4 Elastic force

Understand, think, search…

N3

N1

Force?

4

Fe = P

ä 3.2 Normal force

Solutions to all the numeric activities are on anayaeducacion.es.

The icons included with some activities indicate the keys to the project.

Unit

Suspended bodies

ä 3.3 Tension

N3 = P3

The normal force cancels out the weight force.

ditch. The plank can withstand a maximum force of 900 N before it breaks. What is the maximum mass a person can have to be able to cross it?

26 A cable can support a maximum tension of 1 200 N.

a) What is the elastic constant of this spring? b) How long will it be if we hang 10 kg from it?

29

Make an infographic that shows the differences between mass and weight.

Can we hang a 125 kg sofa from it?

There is a resource on everyday forces on anayaeducacion.es.

113

KEYS

PROJECT

SDG

2

SDG Commitment Discover the Sustainable Development Goals and be an active part of our commitment to make a more equal and liveable world.

Developing thinking Work on strategies for thinking: reflect on the content you are learning, generate ideas, organise them, debate them, explain them…

Cooperative learning Get involved in your learning and participate in the group’s learning; you will find that cooperating improves performance and harmony in the class.

Emotional education Get to know yourself; identify the situations that bring up complicated emotions and manage them with constructive, self-affirming experiences.

A research project in each unit to implement the application of the scientific method and encourage the acquisition of skills and attitudes necessary for scientific work.

Science workshop SCIENCE WORKSHO

Research project

5. NATURE OF FORCES

Atomic mass

The mass of an atom of a specific element.

Alternating current

Atomic number, Z

Number of protons in the nucleus of an atom of an element.

Alternator

Mass number, A

It is the sum of protons and neutrons of an atom of an element.

2. CHEMICAL SUBSTANCES 2. ATOMS BOND Chemical bond

Process involving forces of attraction through which two or more elements create a new substance.

Octet rule

When two atoms bond, they tend to accommodate eight electrons in their last shell, except H, Li and Be which are left with two electrons. This provides them with chemical stability.

Integrated circuit Transistor

Formula unit mass

Sum of the masses of the atoms that are part of the formula of the substance.

Molecular mass

The mass of the molecule of a substance.

Procedure

Final reflection

3. CHEMICAL REACTIONS 1. CHANGES IN THE COMPOSITION OF SUBSTANCES Substance (or substances) that appears as a result of a chemical reaction.

Reaction

Process in which reagents rearrange to form new substances, called products.

Reagent

Initial substance (or substances) that reacts in a chemical change to generate new ones.

Physical quantity defined through magnitude. The value is followed by its unit.

Physical quantity defined through magnitude and direction. The value of the vector is proportional to its length and followed by its unit.

Line that carries electricity to every home.

Wire within the distribution panel where the current enters the home. It can be brown, black or grey.

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Unit

ä 2.7 Marine power stations The mechanical energy from seawater is harnessed in these power stations. Wave energy is that which harnesses the energy transported by sea waves (upper-right image). No method has been established to extract this energy, and nowadays there are different ways to do so.

This type of power station uses a renewable source of energy, as the potential energy of water is used. It does not produce pollution, but the required flooding of areas modifies the environment, consequently destroying entire ecosystems.

The other energy we can harness from oceans is tidal, generated by the movement of masses of water in tides. To do this, we need to find bays which flood in each high tide. Here a barrage* is built and the energy produced by water passes through holes with a turbine in each one of them, transmitting the movement to an alternator.

• Through the use of photovoltaic panels. Of all the electric power stations, the photovoltaic is the only one that does not use an alternator, as the photovoltaic panels have the property to produce electricity directly from the light they absorb.

These two types of power station use renewable sources of energy.

Working with pictures

Draw a waterfall from a high tank, and indicate which form of energy the water has at different points of the fall.

Together with photovoltaic solar power stations, this is the great effort of renewable energy in Spain. It involves installing wind turbines in strategic zones, taking up large areas of land. Part of the kinetic energy of the wind moves the blades of the wind turbine. This movement makes the alternator turn, producing electric current (lower-right image).

Energy from water and wind

Hydroelectric power station

Wind power station Rotor

ä 2.8 Geothermal power station In some places that have hot springs, such as Iceland, they use it to carry the water to homes. In this way they do not have to heat water and save costs.

There are also countries that use the high temperatures of the subsoil to create a closed circuit of water which is injected from the surface to the hot source, obtaining steam which rises and which will move the turbines of the generator.

Wire within the distribution panel connected to the ground. It is colour blue.

Device that compares the current of the fase with that one of the neutral wire. They should be equal.

Service drop

Main tube that connects three wires with the street electric distribution grid.

Service panel

Electrical access point to buildings with different fuses that can cut off electricity if an overload takes place.

Drives

8 Dam Transformer

Alternator Transformer Generator

Turbine

The water moves the blades of the turbine of the generator.

9

There is no one standard design of device to collect wave energy. Look up information on the main methods that are used and draw a diagram of each one.

The compare advantages and disadvantages.

Which countries have geothermal power stations?

In which areas of the planet can we find them? Do you think they could be used in Spain? Look up information on this matter.

11

Geothermal power station

2 Summarise information with your drawing. In your notebook, draw a diagram of the forces that apply between two masses and two electric charges.

Electromagnetism connect

electricity

magnetism present in

present in

Timeline carries out

Cold water

Hot water

can be nort

charged objects is due to

magnetic charge

electric current

Circle of viewpoints. According to the geographical and climatological features of Andalusia, which type of renewable energy do you think would be most logical to invest in? Make a list of the reasons that support your suggestion and prepare yourself to defend it in the classroom.

can induce

interact according to

1 How far away from the Earth would you have to be for its gravitational attraction to have no effect?

2 An object of 120 kg weighs 1 064.4 N on Venus. What is the acceleration of gravity on the surface of Venus?

Explain what this value means.

3 Two objects of masses m1 and m2, separated by a distance of d0, are gravitationally attracted with a force F0. How would the force change if: a) The mass of object 1 were doubled. b) The masses of both objects were doubled. c) The masses were closer by half the distance.

quarters water, this source of energy is not used very often. Look for information on the Internet and draw up a list of the countries that are using tidal energy.

4 The Earth-Moon system is kept together through gravitational attraction. The diameters of the astronomical objects are, DE = 12 742 km and DM = 3 474 km, and the distance from the middle of each star is dEM = 384 400 km.

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11 Someone at the highest part of a bell tower lets balls A and B fall at the same time. The balls are the same, but made of different materials, so ball A has double the mass of ball B. Suppose that the resistance of the air is negligible. Show which of the following statements are true: a) Ball A weighs the double of ball B. b) Ball A will touch the ground first. c) Ball A will have a greater impact on the ground than ball B. 12 Observe the following image of a balanced scale.

Just as the balance is in the image, explain if it would remain balanced if it were to be taken to the moon.

can be

south

Systemic diagram, etc…

12 Although we live on a planet where its surface is three

Search for “Oumuamua” and explain what it is believed to be, and what other imaginative theories there are for its existence.

electric poles

Coulomb’s law

In accordance with goal 15.5, another type of wind turbine has been designed which would avoid killing birds. Look up how these new wind turbines are in the development stage and write a short report describing them.

metals

have two

in disorganised movement it is

a) Draw a diagram of the scale of 1 cm: 25 000 km. b) Show the force of attraction in each of the stars.

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positive pole

6 The planet Mars has a diameter of 6 794.4 km. It is known that the gravity on its surface is 3.7 N/kg.

Determine the mass of the planet and compare it to the mass of the Earth; ME = 5 972 · 1024 kg.

7 Gravity on the surface of the dwarf planet Pluto is 0.6 N/kg. Its mass is 1.25 · 1022 kg. Calculate its diameter.

8 Jupiter is the largest planet in the solar system and is a gaseous planet. Its mass is 1.9 · 1027 kg. It has 79 known satellites. How do you think the orbit of these satellites would be affected if the diameter of the planet were to shrink down to half the size while conserving its mass?

9

1 kg

negative pole

5 Mercury has a mass of 3.3 · 1023 kg, and its orbit has an average radius of 0.39 au, whereas Venus has a mass of 4.87 · 1024 kg, and the average radius of an orbit is 0.72 au. Determine the maximum gravitational force with which these two planets interact.

Search for which conditions a star must have for it to fit in the category of a planet. Which of these requirements do dwarf planets not fulfil?

Solutions to the numeric activities are on anayaeducacion.es.

Questions on the essential aspects of the unit so that you may make your own summary.

Trust in your skills and knowledge, develop creativity, adapt to changing situations and have a proactive and responsible attitude.

iron monosulphide.

a) Write its chemical formula. b) Is it a molecular substance or is it a crystal? Interpret the meaning of its chemical formula.

Unit

has similar properties to

Look up all the objectives goals regarding goal 7 “Affordable and non-polluting energy” on anayaeducacion.es.

Enterprising culture

3 The substance that has been formed in the crucible is

The experiences of the Practical Work section to remember and apply what was studied in the initial unit of the book and, at the same time, work on the contents developed in the unit.

10

Gravitational force

The wind moves the blades of the wind turbine.

168

Visual organizer of the content Law of conservation

10

points of view: observation and the application of models seen in the unit.

Systemic diagram

1 In your notebook, correct the following mind map in which the mistakes are marked in red.

Brazil has opted for a model in which the waves move buoys fixed to mechanical arms.

The source of energy is the thermal energy from hot sources of the subsoil.

Round table. Work in groups and look for information to find out the current status of research on fusion power stations: where they are being located, what date we expect to have them available and their benefits. Show your findings on a wall.

same properties? Explain the experimental evidence you have found.

2 Describe what has happened in the crucible from two

REVIEW

barrage: a wall built across a river to store water

7

1 Do the final chemical mixture and compound have the

review

ä 2.9 Biomass thermal power station

F ocus on English

Draw conclusions...

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en to strength Activities d ie d u st n bee w h at h a s rk o ferent w using dif strategies.

ORGANISING MY IDEAS

A biomass power station is a thermal power station in which biomass is burned instead of fossil fuel.

This deals with a renewable source of energy, as the fuel is regenerated more quickly than it is consumed; however, it produces polluting gases.

• Carry out the experiments that you have suggested to differentiate between the mixture and the compound.

Write the experimental approach beforehand and ask your teacher about any additional experiment that can be carried out.

resources from to choose .

Remember for your portfolio this unit to

Understand, think, search…

Generator

Blade

Sluice gate

7

Wave power station

Organic waste, such as waste from forests, cattle, farming, etc. is utilised to produce a fuel which will be burned.

ä 2.6 Wind power station Wind farm in Cadiz.

• Place two spatulas of sulphur and one of iron shavings in a beaker, mix them with a glass rod and label it as “mixture”.

• Prepare the same mixture as in the previous point, but this time in the crucible. Heat the metal rod on the flame of the Bunsen burner (using the safety elements) and then place the rod in the crucible. Observe the phenomena that take place and write down the results in your notebook.

Device installed in the control and protection panel (CPP) that limits the maximum power contracted by the user.

Neutral wire Residual-current device

183

In the first hydroelectric power stations, dammed water was left to fall in order to move the turbines of the generator; in current ones, it is pressurized through some pipes in the lower part of the dam (bottom-left image).

• A boiler with water heats up by means of large mirrors which focus light from the sun onto it until the water boils, and the steam redirected through pipes moves the turbines of the generator. This type of electric power station is the solar thermal power station.

• When you have obtained the chemical compound, it will be at a high temperature. Considerer enough time in your planning for the compound to cool down.

Results

Individual derivation

Main switch

Scalar quantity Vector quantity

ä 2.4 Hydroelectric power station

In solar power stations, the electromagnetic energy coming from the sun is transformed into electrical energy by means of two mechanisms:

• In order to form the compound formed by iron and sulphur, you must heat the mixture using a metal rod which has been previously heated. Use protective gloves for hot elements and safety goggles, and take all necessary precautions.

From the information you have found make some boards for the classroom Set of individual electrical meters thatwhich measures thethe energy consumption each home connect related topics to theofMillennium Goals of this project. application for society and some in a building.

An individual comes out from each meter. controversy.

Finding out bothderivationDecide among all of you the structure of these boards and the medium us tothat have a criticaleach viewcircuit ofyou Automatic circuit breaker allows Device protects theare home fromthem. overloads or shortgoingindividually to use to make about their use and applications. circuits.

List pros and cons of the use of Discussion, conclusions presenting Distribution board Installation where the individual derivations enter through to carryand electricity to everyyour work synthetic fertilizers in agriculture.

Organise an exhibition and round table with another class group to show home.

2 The problems that affect the whole your work and use it as a basis for critical discussion.

Earth wire Wireworldwide connected to the all ground to prevent electrocutions. society concern of Write up minutes from the round table which include conclusions and us Device who are that part of it. As a all future General circuit breaker protects the circuits installed in the home from overloads or shortcommitments. responsible citizen, drawoff upthe a list circuits by cutting current in all of them. with your conclusions in this work.

General supply line Cable that comes from the service panel and reaches the array of electrical meters.

Life wire

Additionally, hydrochloric acid and test tubes

Guidelines

1 All discoveries have a beneficial

Product

Materials • Sulphur • Iron shavings • Two beakers • Watch glass • Crucible • Spatula • Bunsen burner • Steel rod • Magnet • Gloves for handling hot elements • Safety goggles

In your laboratory report, you can attach a photograph of each elementary substance, of their mixture and of the compound obtained in the experiment.

Puzzles

• The life of Fritz Haber and the controversy with his Nobel Prize for Chemistry.

7. ENERGY SOURCES

5. ELECTRICAL ENERGY IN OUR HOMES

Do you think Physics and Chemistry and English have anything in common? Discover how language, physics and chemistry are linked so you can learn them all.

ä 2.5 Solar power station

Our proposal One characteristic of iron is that it can be attracted by a magnet. This property will allow us to differentiate between iron in an elementary state and a compound in which iron is present.

Array of electrical meters

Focus on English

There are many degrees and diplomas related to renewable energies, which range from different vocational training certificates to university degrees and masters. Find out which ones you can study at any Andalusian university. Then, look up job offers in your autonomous community linked to this sector and share them in class.

Remember any property of sulphur and iron which allows you to identify them and think how to check if new substances are obtained when you heat the mixture.

Carry out documentary research on the repercussions of using synthetic fertilizers.

182

Renewable energies

Your proposal

Organise the class into small work groups and look up the following subjects on the Internet: A basic electronic component which its principal characteristic is low resistance if • Eutrophication, to achieve goal 6.3 of the SDG. current travels in one direction and high resistance in the other.

• Organic agriculture and access to food, following goal 2.3 of the SDG. Microelectronic circuit made out of multiple transistors designed to carry out different The effects of intensive agriculture on the environment, in order to tasks within a circuit. Also called chip• or microchip. achieve the sustainable management and efficient use of natural Device that enables the amplification of a signal, for instance, electric current. resources (goal 12.2 of the SDG).

6. ELECTRONICS Diode

5. CHEMICAL FORMULAS

1. FORCES

In Spain more than one thousand companies are related to the renewable energy sector, creating thousands of jobs per year. The figures are on the increase and this broad and growing sector is needing more and more specialised professionals.

When we mix iron and sulphur we get a heterogeneous mixture.

However, if we heat this mixture, do we get a new substance? How can we know if this is a new substance?

In 1913, German chemists Fritz Haber and Carl Bosch managed to fix nitrogen from the atmosphere (N2) in the form of ammonia (NH3) developing a very important industrial process, known as the Bosch-Haber process of ammonia synthesis.

Periodically change in the direction of the electric current.

Later, this process was used to synthesise fertilizers in the rest of the A device that produces electric current based on the motion of a magnet in relation to world, which drastically changed the worldwide capacity of agricultural a ring made of an electrical conductor material. production in the 20th century.

Non-permanent magnets that can be activated through an electric circuit and Objective deactivated by interrupting it.

Anomalous growth of algae resulting from eutrophication in the Guadalete River.

6. CIRCUITS

4. FORCE AND ITS EFFECTS

2 ELECTRICAL POWER STATIONS

Approaching the problem

4. ELECTROMAGNETISM

Electromagnet

We learn the relevant terms that are underlined in the units with a clear definition.

simple substances and compounds

Fertilizers are natural or synthetic substances which are added to the arable land in order to enrich it in one, or various, of the three elements needed for the life of plants: nitrogen, phosphorus and potassium.

Until the 20th century, nitrogen fertilizers of natural origin were used: guano (from Peru) and saltpetre (sodium nitrate from deposits in Chile, marketed with the name Chilean nitrate).

4. THE NUCLEUS OF THE ATOM

Glossary

PRACTICAL WORK

Introduction

FERTILIZER exPLOSIVES

Glossary 1. THE ATOM

2

Unit

P

Academic and professional

500 g

5

Electrostatic force 16 Answer the following questions: a) What is the property of matter called in which two objects electrically interact? b) What are the two kinds of charges called? c) Do the charges of different signs repel or attract?

And what if the signs were the same?

17 Does a positively charged object have negative charges? And does it have positive charges? Explain your answer.

18 Explain the meaning of the following phrase: “The electric charge is conserved in an isolated system.”

19 The triboelectric series allows us to determine the kind of charge a material acquires (positive or negative) when it is rubbed with another. So, if two materials in the table come into contact, the one that is upper in the series shall transfer electrons to the other, which will be left with a positive charge, and the other material will acquire a negative charge.

Furthermore, the more separated the materials in the table are, more charge is transferred from one to the other. Some materials in the series are: Triboelectric series (from top to bottom and from left to right) Greater positive charge 1. Air

5. Glass

10. Silk

6. Quartz

11. Paper

2. Human skin

7. Mica

12. No charge

17. PVC

Search for the definition of exoplanet and its habitable zone.

3. Leather

8. Human hair

13. Rubber balloon

18. Teflon

15 Look at the following image of an advertisement for a brand of paint. Do you think there is something that is not physically acceptable?

4. Rabbit skin

9. Wool

14. Copper

Greater negative charge

13 What do you think would happen to the planets in the solar system if the Sun were to suddenly disappear for some mysterious reason? Would we notice what happened in that moment when the Sun disappeared?

14

15. Sulphur

16. Silver

Answer these questions: a) What happens when we rub a silk cloth and a glass rod together, and then we touch a neutral metal sphere hanging from a pendulum? b) What would happen if we repeat the same procedure, but use leather instead of silk? c) Lastly, if we move the two spheres near the two pendulums, will they attract or repel?

137

Images to observe and interpret.

ICT

orientation

Evaluation

Linguistic Plan

Learn how to obtain information, select it and apply it; to plan, manage and work on projects; to collaborate online in an ethical and safe manner.

Evaluate your personal skills, discover and awaken your calling, train yourself to make decisions and learn to choose between different options.

Discover different strategies to analyse what you have learnt and how you learnt it; train yourself to take responsibility or overcome difficulties.

Use your communication skills in the different types of text that you will see.

Language is always present, communicate!

3

The resource bank is LIKE THIS www.anayaeducacion.es A space with resources, techniques and activities, designed to strengthen your knowledge.

Access the resource bank by registering at anayaeducacion.es.

You just need to have an email, the code indicated on the first page of this book and the permission of a parent or a legal guardian.

More about the keys

Resources related to

THE KEYS of the project SDG

SDG Commitment, with microvideos that will help you know what are the targets for reaching the Sustainable Development Goals worked on in this project.

Linguistic Plan, with infographics that will give you models to work with the four linguistic skills, using different types of texts (descriptive, narrative, explanatory, etc.).

Cooperative learning Preparing for the task In small groups, of four or five members: 1 All the members of the team will review how the assigned task can be accomplished.

2 To do this, the steps can be shared out to each team member who then in turn will explain how each part of the process can be done to the others. The others listen and participate if they think they can contribute something.

Authorship / adaptation : Variant of the Educational Innovation Laboratory of the colegio Ártica - David and Roger Johnson.

Developing thinking, where explanations are included on how to apply the different strategies for thinking proposed in the project.

3 Once everyone is in agreement on how to do each part, you will all complete the tasks and, finally, verify, among everyone, that you have solved it correctly.

Cooperative learning, which includes the description of the cooperative learning techniques proposed in the project.

Emotional education, with resources to support you with overcoming worries generated in different situations in your learning process (beginning of the school year, taking a test, etc.).

Thinking techniques Logic Wheel This thinking technique will help you to establish phases when analysing specific content that you have to study.

Identify What is it? What is it like? Are there different types?

By following a logical sequence (the logic wheel), and by asking yourself a series of questions in each phase, you can:

1

• Identify content by asking yourself: What is it? What is it like?

Are there different types?

• Compare the content by formulating questions such as: In what way is it similar to ...? In what way is it different from ...?

• Establish cause-effect relationships by asking yourself questions such as: Why? What impact does it have ...?

• Argue, assess and ask yourself questions such as: What conclusions can be drawn after the analysis? What can be assessed or scored about it?

Doing a data dump of these questions into a graphic organiser will help you.

Authorship: Hernández, P., and García, L. A.; adapted by Escamilla, A.

Compare

Argue, assess What can we conclude?

4

Logic wheel

2

3 Establish cause-effect relationships Why? What impact does it have ...?

In what way is it similar to ...?

In what way is it different from ...?

ICT, by using data sheets that will reinforce your healthy, correct and safe use of information and communication technologies.

Academic and professional orientation, with information on different professions linked to the subject content.

Evaluation, which includes resources for your portfolio, as well as rubrics and targets that will facilitate your self-evaluation.

4

NOTEWORTHY

resources in the material A utonomous-community specific contents W hat you should know T o study L earn by playing Virtual laboratories and simulations V ideos P resentations S elf-assessments S olutions

Resources classified

by unit

All the resources are classified so that you can easily locate the ones related with each section of your unit.

5

course contents Scientific Knowledge

Page 8

3

Chemical reactions

Page 86

The use of science ................................................................... 8 1. What is science? ................................................................... 10 2. Physics and Chemistry ....................................................... 13 3. Physical quantities. Units and measurements .......... 14 4. Measuring instruments. Errors ........................................ 16 5. Multiples and submultiples .............................................. 19 6. The language of science ................................................... 20 7. Laboratory equipment. Safety rules ............................. 22

Chemistry and global warming .......................................... 86 1. Changes in the composition of substances ............... 88 2. Atomic theory of chemical reactions ........................... 90 3. Chemical equations ............................................................ 92 4. Laws of chemical combination and chemical equations ................................................................................ 94 5. Amount of substance ......................................................... 96 6. Chemistry, environment and society ............................ 98

Research project.

Archimedes and buoyancy ................................................... 24

Research project. CO2 sinks .................................................. 100

Practical work. Does aluminum float in mercury? ....... 25

Practical work. Chemical reactions with gaseous substances ................................................................................... 101

Review .......................................................................................... 26

Review .......................................................................................... 102

1

the atom

Page 30

Scientific theory and paradigm shifts ............................. 30 1. First ideas about the atom ................................................ 32 2. From the electrical nature of matter to the first atomic model ......................................................................... 34 3. From radioactivity to the nuclear model of the atom .............................................................................................. 36 4. The nucleus of the atom .................................................... 38 5. Classification of the elements .......................................... 40 6. Atomic orbitals ...................................................................... 42 7. Applications of radioactive isotopes ............................. 44 Research project. Radioactive waste ..................................... 46 Practical work. Chemistry of fireworks ............................. 47 Review .......................................................................................... 48

2

chemical substances

Page 52

The food industry ..................................................................... 52 1. Simple substances and compounds ............................. 54 2. Atoms bond ........................................................................... 56 3. Chemical bond ...................................................................... 58 4. Molecules and crystals ....................................................... 60 5. Chemical formulas ............................................................... 62 6. Industrial, biomedical and technological applications ............................................................................ 64 Research project. Fertilizer explosives.................................. 66

4

Force and its effects

Page 106

Understanding the forces of nature ................................. 106 1. Forces ....................................................................................... 108 2. Deformation ........................................................................... 110 3. Everyday forces .................................................................... 112 Research project.

The acceleration of gravity ................................................... 116 Practical work.

Elastic deformation .................................................................. 117 Review .......................................................................................... 118

5

Nature of forces

Page 120

Geolocation ................................................................................ 120 1. Gravitational force ............................................................... 122 2. Electrostatic force ............................................................... 126 3. Magnetic force ...................................................................... 130 4. Electromagnetism ............................................................... 132

Practical work. Simple substances and compounds ... 67

Research project.

Magnetic force of an electromagnet ................................. 134

Review .......................................................................................... 68

Practical work. Where is North? ......................................... 135

Appendix. Nomenclature ...................................................... 72

Review .......................................................................................... 136

6

Circuits

Page 140

7

Energy sources

Page 162

The transistor ............................................................................. 140 1. Electric current ..................................................................... 142 2. Electric circuit ....................................................................... 144 3. Ohm’s Law .............................................................................. 146 4. Kirchhoff’s Laws ................................................................... 148 5. Electric devices .................................................................... 152 6. Electronics .............................................................................. 154

Electric cars ................................................................................ 162 1. Rational use of energy ....................................................... 164 2. Electrical power stations .................................................. 166 3. Transport and distribution of electrical energy ....... 170 4. Electrical energy and power ........................................... 172 5. Electrical energy in our homes ....................................... 174

Research project.

Evolution of microprocessors .............................................. 156

Practical work. Energy for cooking ................................... 177

Practical work. Measuring resistances ............................. 157

Research project. Types of lamps ..................................... 176 Review .......................................................................................... 178

Review .......................................................................................... 158

Annex • Glossary ...................................................................................... 182

3

CHEMICAL REACTIONS Reading and listening

Chemistry and global warming Chemistry is the scientific discipline that deals with chemical transformations; the change of substances from one to another resulting from reactions. As in many other fields of study, what forms the core of chemistry nowadays is the result of many years of research and practical work. Centuries ago, the predecessor of chemistry was alchemy, a non-scientific study of matter with different aims, for instance, finding the elixir of immortality. Although alchemy did not evolve, it set the basis that allowed asking relevant questions, thus igniting the development of the field.

Research laboratories are places where cutting-edge chemistry takes place. Some objectives encompass developing techniques to enhance the efficiency of chemical reactions that accelerate or slow down industrial processes, studying reactions that take place in the environment, as well as designing specific reactions that could impact entire societies.

Global warming could potentially jeopardise the existence of human beings, thus one of our biggest concerns. The origin of global warming takes place in the emission of considerable amounts of carbon dioxide to the atmosphere exceeding the limit that nature can absorb. A consequence of these emissions reflects on an increase in the average temperature of the planet. This situation has been taking place ever since industrial revolutions and has increased with the establishment and proliferation of industries all around the world.

1 What is the difference between alchemy and chemistry?

2 What is the main point of the introduction?

3 Find two synonyms to the word ‘jeopardise.’

4 Name four different types of industries. Give an example of each.

86

Speaking An interview

5

Global warming and chemical reactions are not only affecting our atmosphere, the impact is also polluting our oceans. For this reason, SDG 14 focuses on ‘life below water.’

In pairs, imagine one person is a journalist and the other an expert on climate change. Use the following information to ask and answer questions on how people can conserve and sustainably use the world’s oceans, seas and marine resources.

For open ocean and deep sea areas, sustainability can be achieved only through increased international cooperation to protect vulnerable habitats. Establishing comprehensive, effective and equitably managed systems of governmentprotected areas should be pursued to conserve biodiversity and ensure a sustainable future for the fishing industry.

On a local level, we should make ocean-friendly choices when buying products or eating food derived from oceans and consume only what we need. Selecting certified products is a good place to start.

Making small changes in our daily lives, like taking public transport and unplugging electronics saves energy. These actions reduce our carbon footprint, a factor that contributes to rising sea levels.

We should eliminate plastic usage as much as possible and organize beach clean-ups. Most importantly, we can spread the message about how important marine life is and why we need to protect it.

Source: https://www.un.org/sustainabledevelopment/wp-content/ uploads/2018/09/14.pdf

What can we do to take of our oceans and seas?

We can use less plastic.

Writing An infographic

6

Based on the previous information and on deeper research, create an infographic to inform people on specific actions they can take to conserve and sustainably use the world’s oceans, seas and marine resources.

NK E BANK A B E G A ANGU LANGUAG L ANK ANK GE BANK B B E E G G A A U U GUA K LANG ANG N L A L AN GE BANK 87 ANK GE BANK B B E E G G A A U U G A LAN LANG LANGUA LANGU

1 CHANGES IN THE COMPOSITION OF SUBSTANCES

ä 1.1. Chemical changes As we have learned, there are changes in matter where substances do not change; in other words, no new substance appears. We call these physical changes. But there is another kind of change where some substances are transformed into different ones; we call these chemical changes: Chemical changes, also called chemical reactions, are those which cause new substances to appear.

Therefore, we say a chemical reaction has taken place when: • The substances that were present before the change combine with each other and, partly, disappear. These substances are known as the reagents of the reaction.

• Due to the combination of reagents, one or several new substances appear which were not present before the change.

These substances are the products of the reaction.

A chemical reaction is any process where one or more substances are transformed into one or more substances.

The reagents transform into the products.

ä 1.2 Diversity of chemical reactions There is an infinite number of chemical reactions and criteria to classify them; for example, depending on the number of reagents and products: if there is a single reagent which becomes two products, there is a decomposition reaction, and, on the contrary, if two or more reagents become one product, there is a synthesis reaction.

Depending on the purpose of the reaction, it can be interesting to consider them as natural reactions, when no anthropogenic factors intervene; artificial reactions, if they occur due to human actions; reactions in aqueous solution, when substances are dissolved in water; or in vivo, reactions, such as those that take place inside cells.

Diversity of chemical reactions Glucose insulin

Insulin K+ ATP

Insulin Entrance of Ca2+

Mitochondria Ca2+

88

The synthesis of insulin takes place in the pancreatic cells. It is an in vivo reaction.

Photochemical smog, which causes atmospheric pollution in many cities, is a web of chemical reactions which are produced due to anthropogenic reasons.

Unit

3

ä 1.3 Evidence of chemical reactions At times, it is not obvious that a chemical change is taking place. Because physical changes might be taking place at the same time, it might not be easy to see the appearance of new substances. Some evidence of a chemical change is:

• Energy exchange between the substances which intervene in the chemical reaction and its environment. For instance, in the case of combustion reactions, this energy exchange is noticeable, but it is not so evident in all chemical reactions.

Evidence of a chemical reaction

4

When we notice the formation of bubbles in a glass of tap water, can we conclude that a gaseous substance has been produced as result of a chemical reaction?

1 Presence

or formation of a precipitate. If the reagents are in solution, it might be that the new substance obtained has a lower solubility, so it will precipitate and this may be observed at first sight.

As a result of a chemical reaction, we can obtain

Working with pictures

• Change in the properties of the environment where the reaction takes place. The properties of these new substances are different. For example, a precipitate (solid substance of low solubility) can form as a result of the chemical reaction, or bubbling may appear, if the new substance is a gas (in other words, of a boiling temperature lower than that of the environment).

2 Presence 1 2

Light and energy in the form of heat

3

or formation of substances in different state of aggregation. As in the previous case, if a gas is produced, a bubbling coming out of the solution will be observed.

3 A

change in colour. The appearance of a different colour in the reaction reveals the presence of a new substance.

Chemical 4

Substance of low solubility Gas

Substance of another colour

reactions that cause a great energy exchange are easily detectable, as it is the case of combustion, which exchanges energy in the form of light and heat.

Understand, think, search…

1

Graphic organiser. Chemical change has been defined as the opposite of physical change. But we have learned that some physical changes accompany a chemical change, although not all of them. Draw a Venn diagram to show this relationship between them.

Explain your diagram to the rest of the class.

Check anayaeducacion.es for a resource on the evidence of chemical reactions.

2

I see, I think, I ask myself. When we take a jug of lemonade out of the fridge, we may notice the formation of a precipitate at the bottom of the jug. Can we conclude that a chemical reaction has taken place?

Observe the evidence, and write the questions that occur to you to answer the activity.

89

2 ATOMIC THEORY OF CHEMICAL REACTIONS

Not all substances react with each other when they come into contact.

Some do so really quickly, others more slowly and others do not react.

Furthermore, there are factors which influence whether a chemical change takes place or not and the rate at which it will happen. In this summary, we will learn the theory that explains, at an atomic scale, how chemical reactions happen and how quickly they do so.

ä 2.1 Collision theory According to Dalton’s atomic theory, a chemical reaction involves a reorganisation of atoms. In order to understand this process, we must keep in mind the ideas of the kinetic theory of matter, according to which matter is formed by particles (atoms, molecules or ions) which are in continuous movement. Due to this movement, particles crash into one another and, in appropriate conditions, the particles of the reagents move apart and regroup to form the products of the reaction.

A chemical reaction takes place if the particles of the reagents crash into one another in an effective way, so that molecular bonds are broken which keep atoms together in the reagents, and new bonds are formed which give rise to products.

For these collisions to be effective, two conditions must be fulfilled: • The collisions between particles must have enough energy.

• The collisions must happen with the proper orientation.

Proper orientation of collisions Effective collision

Molecules get closer with enough energy and proper orientation.

An effective collision is produced.

New bonds are formed giving rise to the molecules of the products.

Non-effective collision

Molecules get closer with enough energy but orientation is not proper.

The collision is not effective.

Molecules of products are not obtained, in other words, there is no chemical reaction.

90

Unit

3

Remember that…

ä 2.2 Factors that affect the reaction rate There are extremely fast chemical reactions, such as explosions, and other slower ones, such as the oxidation of iron.

The rate of a chemical reaction is defined as the variation of the amounts of the products obtained, or of the reagents which disappear, per unit time.

At times, the intention is to promote the formation of certain products that are beneficial to society, such as those obtained by the chemical industry; therefore, the rate of certain reactions is increased.

However, in the case of non-desired reactions, such as food decomposition, the opposite effect is sought, that is to slow down the chemical change.

In both cases, it is indispensable to know which factors influence the reaction rate. Some of them are: • Temperature. When temperature increases, the speed of particles increases, so the energy of the collisions that take place between them also increases, leading to a greater number of effective collisions and, accordingly, an increase in the reaction rate. When the temperature decreases, we get the opposite effect.

From now on, every time we talk about elementary entities, we will be referring to the smallest unit formed by a substance, which can be an atom, a molecule or a group of ions.

Working with pictures Besides temperature and concentration of reagents, there is another factor which affects the reaction rate: the presence of catalysts. Look up information on these substances and explain why they are so important.

Give several examples and share your findings with the rest of the class.

• Concentration of reagents. In reactions that take place in solution, if the concentration of reagents increases, there will be a greater possibility of collisions between particles, and therefore, a faster reaction rate.

Factors which influence reaction rate

Food decomposition reactions are faster at room temperature (right) than inside cooled chambers (left).

The concentration of reagent in the reaction on the right is higher than that on the left, and therefore, the reaction rate is higher.

Understand, think, search…

3

Graphic organiser. Create an outline where you connect the ideas of the kinetic theory of matter and Dalton’s atomic theory with the collision theory of chemical reactions. Write conclusions on the factors which influence the rate of chemical reactions.

4

Think and share with a partner. Reflect and answer these questions: a) Do you think pressure affects the reaction rate if the reagents are gases? b) Will a log of wood burn before the same mass in the form of splinters?

At anayaeducacion.es, there is a resource on the formation of ammonia and another one about the oxidation of an apple.

91

3 CHEMICAL EQUATIONS

A chemical equation is the symbolic representation of a chemical reaction which contains quantitative and qualitative information.

Quantitative information refers to the number of elementary entities (atoms, molecules or ions) of reagents and products which intervene in the reaction. Qualitative information will be that which shows the state of aggregation of substances and the conditions in which the reaction takes place. A chemical equation is made up of: • Chemical formulas of the reagents separated by the ‘+’ sign, the symbol for chemical change (→8) and the formulas of products, also separated by the ‘+’ sign.

• Stoichiometric coefficients, which indicate the number of particles of each substance that intervenes in the reaction. If the value of the coefficient is one unit, it is not written.

To read the quantitative information that a chemical equation contains, it needs to be balanced. The number of atoms of each chemical element intervening in the process must be equal in both the reagents and the products. This is achieved by choosing the appropriate values for the stoichiometric coefficients, as shown in the charts on this page and the following one.

Balancing a chemical reaction We balance the reaction of iron sulphide (II) with oxygen to convert into iron oxide (III) and sulphur dioxide.

Without changing the chemical formulas of both reagents and products, we follow these steps:

REAGENTS Iron sulphide(II)

The elements that only appear in one reagent and one product are chosen and we balance their stoichiometric coefficients. First, the metals and then the nonmetals:

Oxygen

PRODUCTS Iron oxide(III)

Sulphur dioxide

Then, we balance the simple substances, ending in H2 and O2. To do that, we count the number of atoms in the products and we balance the reagents:

Therefore, the stoichiometric coefficients are: 2 FeS + O2 8 Fe2O3 + SO2

2 FeS + O2 8 Fe2O3 + 2 SO2

To avoid fractional coefficients we multiply all the coefficients by the denominator of 2 · (2 FeS + 7 O2 8 Fe2O3 + 2 SO2) 2 the fraction, although both expressions are valid: REAGENTS

92

PRODUCTS

1 Ò 4 = 4 atoms Fe

2 Ò 2 = 4 atoms Fe

1 Ò 4 = 4 atoms S

1 Ò 4 = 4 atoms S

2 Ò 7 = 14 atoms O

3 Ò 2 + 2 Ò 4 = 14 atoms O

2 FeS + 7 O2 8 Fe2O3 + 2 SO2 2

4 FeS + 7 O2 8 2 Fe2O3 + 4 SO2

Wo r k in g w it h p ic t u re s

Why do w e coefficients avoid fractional sto ichiometric in usefulininte chemical equation s? Are the rpretingth y eq contained in a chemic ualitativeinformatio n al equatio Look at th n? e figures on this pa these que ge to answ stions. er

Unit

3

Balancing a combustion reaction For this type of chemical reaction, we will always follow this method. We will use propane combustion as an example. In this chemical reaction, propane combines with oxygen to form carbon dioxide and water. The reagents and products of the reaction are: In order to know the number of molecules of carbon dioxide, we take into account that all the carbon atoms of propane will end up forming part of carbon dioxide.

REAGENTS

Propane

Oxygen

The number of water molecules is determined by the number of hydrogen atoms of propane, which is eight. Therefore, four water molecules are produced.

PRODUCTS

Carbon dioxide

Water

Lastly, there are ten oxygen atoms in the products; therefore, there will be five oxygen molecules in the reagents.

Following this reasoning, we establish the stoichiometric coefficients: C3H8 + O2 8 3 CO2 + H2O

REAGENTS

C3H8 + O2 8 3 CO2 + 4 H2O

PRODUCTS

3 Ò 1 = 3 atoms C

1 Ò 3 = 3 atoms C

2 Ò 5 = 10 atoms O

2 Ò 3 + 1 Ò 4 = 10 atoms O

8 Ò 1 = 8 atoms H

2 Ò 4 = 8 atoms H

C3H8 + 5 O2 8 3 CO2 + 4 H2O

ere n.es th al io c a c u ayaed cing chemic On an n la a pane b urce on pro o r s e e h r t o an is a ns and equatio ion. st combu

Understand, think, search…

5 Write the chemical equation that corresponds to the

a) b) c) d)

following description: ‘Two dihydrogen molecules combine with one dinitrogen molecule to give three ammonia molecules’.

6 Indicate whether the following chemical equations are balanced or not. Correct as necessary:

8 Balance the following chemical equations: a) Ca + H2O 8 Ca(OH)2 + H2 b) Fe (s) + HCl (aq) 8 FeCl3 + H2 (g) c) CH4 (g) + O2 (g) 8 CO2 (g) + H2O (g)

a) 4 NH3 + 6 O2 8 4 NO2 + 6 H2O b) 2 K + 3 H2O 8 2 KOH + 3 H2 c) 4 KMnO4 8 2 K2O + 4 MnO + 5 O2 d) Na2O (s) + H2O (l ) 8 2 NaOH (aq)

7 Which one of these chemical equations corresponds

to the reaction of nickel (II) chloride NiCl2, with sodium hydroxide, NaOH? Solutions for all the numeric activities at anayaeducacion.es.

NiCl2 + NaOH 8 Ni(OH)2 + NaCl NiCl2 +2 NaOH 8 Ni(OH)2 + 2 NaCl NiCl2 + Na2(OH)2 8 Ni(OH)2 + Na2Cl2 2 NiCl2 + NaOH 8 2 Ni(OH)2 + NaCl

9

Glucose fermentation is a type of decomposition reaction; glucose breaks down into ethanol and carbon dioxide. Look up the formula of the three compounds, write down the reaction that takes place and balance it.

Compare your solution with the rest of the class.

93

4 LAWS OF CHEMICAL COMBINATION AND CHEMICAL EQUATIONS

Between 1789 and 1804, the laws of chemical combination were published with empirical laws that establish relationships between the mass of the reagents and of the products in a chemical reaction.

ä 4.1 Law of conservation of mass In 1789, the French scientist A. Lavoisier reached the conclusion that, in a chemical reaction, mass is neither created nor destroyed; only a transformation of substances takes place. This observation can be stated in the following way: In a chemical reaction, the sum of the masses of the reagents is equal to the sum of the masses of the products.

The atomic theory explains this empirical law, since a chemical reaction is only a reorganisation of atoms. No new atoms are created; the atoms of the reagents are organised in a different way to form other substances, the products of the chemical reaction. Thus, the total mass of the reagents will be equal to the total mass of the products (Part 1 of the chart on the next page).

ä 4.2 Law of definite proportions Between 1794 and 1804, J. L. Proust established that, when two or more simple substances react to form a compound, the proportion by mass of the simple substances that reacted always had to be the same. This was verified by changing the masses of reagents in succession and checking that their proportion always remained constant.

In a chemical reaction, the proportion by mass of the reagents and the products is fixed and independent of the amount that reacts.

We can explain this empirical law by taking these facts into account: • The composition of each chemical substance is constant and expressed in its chemical formula.

• The average atomic mass is a characteristic of each chemical element.

The mass of a compound is obtained from the mass of the elements which make it up.

• The number of elementary entities of each substance that intervenes in the chemical reaction is constant and is expressed by means of the stoichiometric coefficients in the chemical equation.

Review what is explained in Part 2 of the chart on the next page.

Understand, think, search…

10 Knowing the average atomic masses of hydrogen

12 In the combustion reactions of wood in a chimney, we

11 From your answer to the previous exercise, verify that

13

(1 u) and nitrogen (14 u), does the formation of ammonia (NH3) from dihydrogen (H2) and dinitrogen (N2) comply with the law of conservation of mass?

the law of definite proportions is satisfied if we know that 7.5 u of dihydrogen combine with 35 u of dinitrogen to obtain 42.5 u of ammonia.

94

obtain ashes. The mass of ashes is lower than the mass of burned wood. Why does this happen? Is the law of conservation of mass satisfied?

Explain the meaning of ‘empirical law’ and ‘theory’.

What is the difference between an empirical law and a theory? Give an example of each case to back your statement.

Unit

3

The laws of chemical combination and chemical equations With this example, we prove the relationship between the laws of chemical combination (law of conservation of mass and law

of definite proportions), and the information obtained from a chemical equation.

Ammonia (NH3) combines with oxygen (O2) to give nitrogen monoxide (NO) and water (H2O).

Part 1

4 NH3 + 5 O2 8 4 NO + 6 H2O

Atomic mass

No. atoms in reagents

Balanced chemical equation.

No. atoms in products

N

14 u

4·1=4

N

4·1=4

H

1u

4 · 3 = 12

H

6 · 2 =12

O

16 u

5 · 2 = 10

O

4 · 1 + 6 · 1 = 10

REAGENTS

We check that the chemical equation is balanced. We add the average atomic mass data, which will be necessary later on.

PRODUCTS

NH3

O2

NO

H2O

14 + 3 · 1 = 17 u

2 · 16 = 32 u

14 + 16 = 30 u

2 · 1 + 16 = 18 u

17 u · 4 = 68 u

32 u · 5 = 160 u

30 u · 4 = 120 u

18 u · 6 = 108 u

68 u + 160 u = 228 u

120 u + 108 u = 228 u

We calculate the molecular mass from the average atomic mass.

We calculate the mass of each substance in the reaction from its molecular mass and stoichiometric coefficient.

We check that the law of conservation of mass is satisfied.

Part 2 NH3

O2

NO

H2O

68 u

160 u

120 u

108 u

Proportion between reagents mNH3 mO2

=

68 160

=

From the molecular masses of the substances that intervene in the reaction, we calculate the proportion between them.

These proportions remain constant for any mass, therefore obeying the law of definite proportions.

Proportion between products

17

mNO

40

mH2O

=

120 108

=

10 9

Repeat the calculations from the equation:

Proportion between reagents and products mNH3 mNO

=

68 120

=

17 30

;

mNH3 mH O 2

=

68 108

=

mO2 160 4 = = ; m NO 120 3 27 17

;

mO2 mH2O

=

160 108

=

40 27

On anayaeducacion.es there is a resource on the laws of chemical combination.

2 NH3 +

5 O 8 2 NO + 3 H2O 2 2

95

5 A chemical reaction does not take place between a few particles; the number that intervenes is enormous, therefore, it is not practical to use the atomic mass unit. For that reason, this will be quantified in a different way.

AMOUNT OF SUBSTANCE

ä 5.1 Amount of substance

Amount of substance and mass

The amount that measures the number of elementary entities of a substance is called amount of substance and its unit in the SI is the mole.

The property of matter that represents the amount of substance is not mass, but the number of particles that make up a certain extent of substance.

As the mass of these particles is so small, the number of entities that make them up, for example, a gram of any substance is enormous. Moreover, this number will be different from one substance to another, as the elementary entities that make them up have different masses.

The quantity of grapes and chickpeas is the same; however, the mass of that quantity is different, since the mass of a grape is different from that of a chickpea.

One mole contains exactly 6.022 140 76 · 1023 elementary entities. This figure is called Avogadro’s number, NA.

Mass of a mole

ä 5.2 Molar mass

The value of molar mass of a substance numerically matches the molecular mass, or the mass of the formula unit, of that substance.

Molecular mass Substance or formula mass/u

To establish the relationship between the mass of a substance and the present amount of that substance, we use the molar mass.

The molar mass, M, of a substance is the mass of one mole of that substance, in other words, the mass of 6.022 140 76 · 1023 elementary entities of said substance. Their units in the SI are kg/mol, although g/mol is used more often.

Molar mass/ (g/mol)

Au

196.97

196.97

KCl

74.6

74.6

NO2

46.0

46.0

The molar mass enables calculations to be made at a macroscopic scale from combinations of units of atomic scale. The relationship between amount of substance, n, and molar mass, M, is as follows: n (mol) =

m (g) M (g/mol)

Mass, amount of substance and number of elementary entities For a mole of acetaldehyde (ethanal, C2H4O), we know that: M (C2H4O) = 12 · 2 + 1 · 4 + 16 · 1 = 44 g/mol 44 g of C2H4O

1 mole of C2H4O

6.022 · 1023 molecules

24 g of C

In 1 mol of C2H4O there is 2 mol of C

1.2044 · 1024 atoms C

Multiplying by M (g/mol)

96

Multiplying by NA

4 g of H

In 1 mol of C2H4O there is 4 mol of H

2.4088 · 1024 atoms H

16 g of O

In 1 mol of C2H4O there is 1 mol of O

6.022 · 1023 atoms O

On anayaeducacion.es there is a resource on the amount of substance quantity.

Unit

3

Chemical reactions and amount of substance Calculate the mass of water, expressed in grams, that is obtained if 204 g of ammonia (NH3) react completely with oxygen, according to the following reaction. Check that the law of conservation of mass is fulfilled.

To calculate the mass of chemical substances intervening in a reaction, we start by its molar mass and the amount of substance of each one of them.

4 NH3

5 O2

+

8

4 NO

DATA: Average atomic mass N H O

DATA: Molar mass

14 u 1u 16 u

N H O

REAGENTS NH3

O2

NO

H2O M (H2O) = 2 · 1 + 16 M (H2O) = 18 g/mol

4 mol

6 mol

m (g) n (mol) = g n Md mol

mNH3 = 17 g/mol · 4 mO2 = 32 g/mol · 5 mNH3 = 68 g mO2 = 160 g

mO2

=

The numerical value of the average atomic mass equals the value of the mass in grams of a mole of atoms (molar mass).

M (NO) = 14 + 16 M (NO) = 30 g/mol

5 mol

mNH3

14 g/mol 1 g/mol 16 g/mol

PRODUCTS

M (NH3) = 14 + 3 · 1 M (O2) = 2 · 16 M (NH3) = 17 g/mol M (O2) = 32 g/mol 4 mol

Balanced chemical equation.

6 H2O

+

mlNH3 mlO2

Stoichiometric coefficients indicate the proportion between reagents and products expressed in amount of substance.

g m (g) = n (mol) · M d mol n

mNO = 30 g/mol · 4 mNO = 120 g

mNH3 mO2

=

mlNH3 mlO2

mH2O = 18 g/mol · 6 mH2O = 108 g

mNH3 mO2

=

160 g O2

From the stoichiometric coefficients and the molar mass of each substance, we calculate the masses of each substance to be able to establish the proportion by mass.

mlNH3 mlO2

We apply the proportion by mass to calculate the masses of the remaining substances from the mass of ammonia.

Data: m'NH3 = 204 g 68 g NH3

We calculate the molar mass of substances from their average atomic masses.

Remember that these proportions always remain constant. =

204 g NH3

68 g NH3

mlO2

120 g NO

mlO2 = 480 g

=

204 g NH3

68 g NH3

mlNO

108 g H2O

mlNO = 360 g

204 g + 480 g = 684 g

=

204 g NH3 mlH2O

mlH2O = 324 g

360 g + 324 g = 684 g

We check that the law of conservation of mass is fulfilled.

Understand, think, search…

14 Calculate the amount of substance present in 350 g of the following substances:

a) Potassium chloride, KCl c) Sucrose, C12H22O11 b) Iron. d) Ozone, O3.

15 Given the following equation, without balancing: N2 (g) + H2 (g) 8 NH3 (g)

Give reasons for whether the following statements are true or false: a) 1 g of N2 reacts with 3 g of H2. b) 1 mole of N2 reacts with 1 mole of H2. c) 1 mole of N2 produces the same amount of NH3. d) 28 g of N2 react with 2 g of H2 to produce 50 g of NH3.

97

6 CHEMISTRY, ENVIRONMENT AND SOCIETY

Chemistry has a great impact on people’s quality of life, as it provides knowledge about new substances with all kinds of applications and contributes to the search for solutions to severe environmental problems.

ä 6.1 Environmental problems Some of these problems take place in the atmosphere as a result of gas emissions in chemical reactions.

Acid rain In some industrial areas, gases are emitted, such as sulphur oxides and nitrogen, which move through the atmosphere and react with the atmospheric water vapour giving rise to corrosive acids, such as sulphuric (H2SO4) and nitric (HNO3) acids. When this solution of gases in water precipitates in the form of rain (called acid rain), it has catastrophic effects.

Besides destroying buildings and historical monuments in towns, it also has a harmful effect in the flora and fauna of forests, rivers and lakes.

Anomalous greenhouse effect The presence of carbon dioxide, CO2, in the Earth’s atmosphere keeps the temperature in our planet within certain values which enable life as we know it. This phenomenon, explained in the figure below, is known as the greenhouse effect.

In recent decades, the amount of CO2 present in the atmosphere has noticeably increased. This is because the carbon cycle has been altered by using oil and coal as sources of energy in chemical combustion reactions.

This greater amount of CO2 means that infrared radiation is retained in excess, which in turn provokes an increase in the average temperature of the atmosphere shown, for instance, with an increase in the frequency and intensity of hurricanes and cyclones. These phenomena are part of what we call climate change, devastating effects on our planet.

The greenhouse effect Part of the radiation that reaches the Earth from the Sun is reflected and another part is absorbed; therefore, the Earth heats up and, in turn, emits infrared radiation, as a result of being at a specific temperature.

The Sun

Part of the solar radiation is reflected by the Earth and the atmosphere

Most infrared radiation is absorbed by the greenhouse gases

Atmosphere

Earth

98

Part of the solar radiation is absorbed by the Earth’s surface and it warms it

The Earth’s surface emits infrared radiation

Greenhouse gases, such as CO2, present in the atmosphere, absorb part of the infrared radiation emitted by the planet and keep this radiation from dissipating outwards, contributing in this way to keep the average temperature of the Earth stable. If the atmosphere did not exist, the Earth’s surface would reach very high temperatures during the day and would be too cold at night, making the existence of life impossible.

At anayaeducacion.es there is a resource on the importance of CO2 in the atmosphere.

Unit

3

Stratospheric and tropospheric ozone Ozone is a molecule that consists of three oxygen atoms, O3, and forms a layer at about 60 km above sea level in the stratosphere. Ozone absorbs a part of the solar radiation that is harmful to health, ultraviolet radiation.

In this process, the ozone molecule breaks down into dioxygen, O2, and monoatomic oxygen, O. The special characteristic of this dissociation is that it is reversible, in other words, ozone can form itself again nearly at once. Therefore, stratospheric ozone makes up the ozone layer, which is kept intact despite ultraviolet radiation.

In the last decades of the past century, a hole in the ozone layer was detected, caused by the presence in the stratosphere of certain gases from human activity: the CFCs. Currently, environmental legislation has set strong limits on the production and use of these gases, and the hole in the ozone layer has been considerably reversed.

On the other hand, since the Industrial Revolution, the presence of ozone in the lowest layer of the atmosphere, the troposphere, has been observed. This comes as a result of the emissions of nitrogen oxides and volatile organic compounds from the industry and motor vehicles. This tropospheric ozone is a pollutant, harmful to health and the environment.

Effects of acid rain in a forest.

ä 6.2 Chemical industry One of the main goals of this industry is the transformation of raw matter into other products which, in turn, will be the raw matter for an infinity of processed products.

The dimensions of our daily life that are influenced by the development of chemistry are numerous, from water purification to the most advanced materials which are part of electronic devices, to polymeric fabrics and materials, car bodies and many more.

Evolution of the ozone layer during 2019.

Understand, think, search…

16

Associative analysis. Besides limiting the use of CFCs, there is another reason behind the reduction of the hole in the ozone layer. Look up information and share it with the rest of the class. How could this situation be improved without harming the planet?

17

Explain the differences between tropospheric and stratospheric ozone. Are there any differences between one molecule and the other?

18

Explain why CO2 is necessary in our atmosphere.

What are the effects of the anomalous greenhouse effect? Search how it relates to goal 13.1 and think of how it could be sorted. Which actions are being carried out at the moment?

19

Look up information about the chemical product used to purify water and its cost. Write up a report and include a conclusion on its use with goal 6.1.

20 The development of the chemical industry is

accompanied by high pollution levels of water, air and soil. Many companies have tried to reduce this negative effect for some time, but it is very difficult due to the high economic costs and the complex adaptation of infrastructures. Look up information about a company that has managed to adapt to the goals established by the UN. Which measures have they adopted? Do you think it was easy?

In teams, design an action plan for any company that has not done this.

21

From what you have learned in the previous exercise, which university degrees and professional training could you study in order to work in the chemical industry?

99

SHOP SCIENCE WORK

Research project CO 2 SINKS

Introduction The increase in the amount of carbon dioxide in the atmosphere has a direct relationship with the increase in the average temperature of the planet. The most obvious and known cause of this increase in carbon dioxide emerges as a result of the combustion of oil and coal utilised in the transformation of chemical energy into electrical energy (goal 13.a).

However, there are other causes linked to the increase in carbon dioxide in the atmosphere, such as the increase in the world population.

1. Could the air that human beings who inhabit this planet exhale in the breathing process influence this fact? Look up the most well-known causes of climate change.

2. Could chemical reactions be developed where CO2 was a reagent and thus reduce its presence in the atmosphere?

3. In which natural process is CO2 a reagent and not a product of the reaction? Could this be the case with industry?

Objective Coral reef in the ocean that serves as a natural CO2 sink.

Research the so-called CO2 sinks and draw conclusions.

Procedure

Puzzle

Divide the class in groups of three. Each person will research one of the following areas, trying to answer the corresponding questions. Use bibliographies and references provided by the teacher.

• Area 1. Impact of overpopulation. What has been the trend in the number of inhabitants of the planet in the last two centuries? How are the population’s habits? What is the impact of overpopulation in climate change? Does it affect lifestyle?

• Area 2. Artificial CO2 sinks. Can climate change be reversed? Is it enough to reduce the emissions of greenhouse gases? What are artificial CO2 sinks?

Presenting your work 1 There will be an exhibition in the school with the infographics of the work groups.

2 Organise a round table for each

area to explain the conclusions. All classmates will elect the members of the round table.

3

100

C&R. Each participant who follows the round tables will write an article which summarises the positions and conclusions drawn.

• Area 3. Autotrophic nutrition. Natural CO2 sinks. What is the carbon cycle? What is autotrophic nutrition? Which living beings carry it out?

Are they considered carbon sinks? Is there any action to promote this way of eliminating carbon dioxide?

Discussion of results Meet the members in each group who have been researching the same area and share your answers to the questions. Then, write a report for your area.

Conclusions Lastly, create an infographic with the pros and cons of each area to address actions related to the SDGs you have been working on.

Unit

3

PRACTICAL WORK CHEMICAL REACTIONS WITH GASEOUS SUBSTANCES

Approaching the problem The presence of gas in a chemical reaction, such as a reagent or product, changes the pressure of the reacting mixture. The difference between this pressure and the atmospheric pressure makes it possible to have proof of the reaction.

Your proposal Prepare the task We will carry out two chemical reactions, one where carbon dioxide is obtained as the product of the reaction [1] and another one in which this gas is one of the reagents of the reaction [2].

NaHCO3(aq) + CH3COOH(aq) 8 CO2(g) + NaCH3COO(aq) + H2O(l ) [1] Sodium bicarbonate

Acetic acid

Sodium acetate

CO2 (g) + 2 NaOH (aq) 8 Na2CO3 (aq) + H2O (l )

[2]

Figure out, how to carry out each one of the reactions so that the difference in pressure before and after the chemical change is obvious. Observe the list of materials we suggest.

Laboratory equipment necessary perform the experiment.

to

Our proposal Pour the vinegar (which contains acetic acid) into the plastic bottle and introduce the sodium bicarbonate into the balloon. Carefully, cover the bottle with the balloon and pour the bicarbonate inside.

Observe the increase in volume of the balloon.

Next, remove the balloon and add the sodium hydroxide. Screw the bottle cap and shake it, to boost contact between the carbon dioxide and the sodium hydroxide which is dissolving in the water. Observe the change in shape of the bottle.

Materials • One 1.5 L flexible plastic bottle • One balloon • Around 100 cm3 of 6° vinegar • 8 g of sodium bicarbonate • 7 g of sodium hydroxide flakes

Guidelines • The masses of reagents that we show in the method exceed the stoichiometric amounts to ensure an adequate reaction rate.

• Alternatively, the bottle can remain open in the first reaction, without using the balloon, so that the carbon

dioxide produced fills the space in the bottle and comes out.

• To ensure this gas has displaced all the air that was inside the bottle, you can introduce a lit match and observe how the flame goes out.

Draw conclusions...

1

1-2-4. Work with your team and answer the following questions:

c) What is the meaning of the symbols in brackets in the chemical equations on this page?

b) Which effect is observed in the bottle when the second reaction takes place? Why?

d) Part of the reagents has not reacted. How do we know this?

101

r to choose Remembe rtfolio. po ur for yo

m this resources fro

unit

REVIEW

ORGANISING MY ideas

Hierarchical concept map

1 Copy the concept map in your notebook, or into an app to prepare concept maps, and do the following: a) Fill in the missing words. b) Explain why the word ‘molecules’ always has an alternative name in the concept map. To do this, think about the type of substances which are not molecular. c) Include a new branch in the indicated place in the concept map (1) to show which kind of change a chemical change is in relation with the composition of matter. d) From the branch in the previous activity, include which ones are pieces of evidence that show a chemical change is taking place.

e) Include in the map, from the place indicated (2), which other symbols can be displayed in a chemical equation. f) From the law of conservation chart, indicate the mathematical way of expressing this law. g) Indicate the relationship between amount of substance and mass in your concept map. To do this, include a branch in the place you consider appropriate. h) Based on orientation, illustrate with a drawing, and include it in the map, an effective collision and another one which is not effective. i) Include in the concept map the constant that connects the number of elementary entities with the amount of substance expressed in mole.

Chemical reactions

are represented by means of

are

Equations ? .................................

(1)

obey

Changes

in which we find

Law of conservation ? .........................................

in which the

Law of ? .........................................

(2) Coefficients ? .................................

Molecules or ? .................................

Chemical formulas

of

which give us information about the

of

Reagents

Collide

Number of Molecules or ? ................................

de

with enough

with proper

Energy

Orientation

and

which are expressed in the unit of amount of substance

giving rise to

? ...........................

Mole

102

of

Molecules or ? .................................

Solutions for all the numeric activities at anayaeducacion.es.

Unit

Changes in composition 1 What does it mean that the nature of matter is altered in a chemical change? Define in your own words the expression nature of matter.

2 When vinegar and bicarbonate come into contact with each other, a gas is released, carbon dioxide, and sodium acetate and water are formed: a) Indicate the reagents of the reaction. b) Indicate the number of products of this reaction.

3 Indicate whether the following statements are true or false and explain why: a) Energy is released in all chemical reactions. b) Chemical reactions only occur naturally in living organisms. c) In a chemical reaction, reagents and products can be in different states of aggregation. d) Chemical reactions which take place in nature create an environmental problem.

4 There are chemical reactions for which the main application is energetic, as a great amount of energy is released during their development. Give an example and explain which environmental problem is associated with them.

3

c) From the previous chart, indicate in which time interval the rate of the chemical reaction is greatest. What do you base your answer on?

Connect this observation with the collision theory.

8

The image. Explain what this represents:

What similarities and differences are there between the previous representation and the following one?

9 How does temperature affect the rate of a chemical reaction? Use the collision theory and kineticmolecular theory on the temperature and the average kinetic energy of particles.

Representation of chemical reactions

Atomic theory of chemical reactions 5 Do all collisions that take place between the reagent particles cause them to break? Which factors does a collision depend on to be effective?

6 Is collision theory compatible with the law of conservation of mass? Both of them explain certain aspects of the chemical reactions, but do they make use of the same scale? Explain your answers.

7 The following table displays the masses of two substances while a chemical reaction takes place over time: Mass A/g

7,5

3,75

2,5

1,88

Mass B/g

1,7

3,4

6,8

13,6

Time/min

1

2

3

4

a) Are substances A and B, reagents or products of the reaction? Justify your answer. b) Graph the data of mass against time, and indicate if this is a linear relationship.

10 One student balances this chemical equation: NO + O2 8 NO2 as follows: NO + O2 8 NO3 Is what he has done right? Why?

11 Balance the following chemical reactions: a) Al + O2 8 Al2O3 c) NH3 + H2SO4 8 (NH4)2SO4 b) SO2 + O2 8 SO3 d) Fe2O3 + H2 8 Fe + H2O 12 Write all the information you can obtain from the following balanced chemical equation: 3 Cl2 (g) + 2 Fe (s) 8 2 FeCl3 (s)

13 Use this table to verify that the reaction in the previous exercise is balanced.

Element

Atoms in reagents

Atoms in products

Cl Fe

103

REVIEW 14 Write the balanced chemical equation from the information in this drawing, where red has been used for oxygen atoms, black for carbon atoms and white for hydrogen atoms.

19 When we heat up 50 g of calcium carbonate, 28 g of calcium oxide and carbon dioxide is formed. a) Which mass of carbon dioxide is formed? b) If we start from 150 g of reagent, which mass is obtained from each product?

20 From the previous exercise, obtain the proportion by mass at which calcium carbonate and calcium oxide react. Could we obtain 56 g of calcium oxide from 60 g of calcium carbonate? Which law have you based your answer to this activity on?

15 Iron disulphide, solid, combines with dioxygen and sulphur dioxide and diiron trioxide, solid, are obtained. Write the balanced chemical equation of this process, indicating the state of aggregation of all substances.

16 Calculate the total number of atoms of each element in the reagents and in the products of the following chemical equations: a) 2 KOH + H2CO3 8 K2CO3 + 2 H2O b) 2 C2H6 + 7 O2 8 4 CO2 + 6 H2O

17 Check that the following chemical reactions are well balanced. If they are not, correct them: a) Zn (s) + Ag2O (s) 8 2 ZnO (s) + Ag (s)

we use 531.75 g of chlorine and 300 g of iron. Are these amounts in stoichiometric ratio? Use the information from the table.

Mass of reagents/g

Mass of products/g

Cl2

Fe

FeCl3

212.7

111.7

324.4

Amount of substance 22 Fill in the following table:

b) 2 NH4NO3 (s) 8 2 N2 (g) + H2O (g) + O2 (g) c) MgSO3 (s) 8 MgO (s) + SO2 (g) d) H2S (g) + SO2 (g) 8 3 S (g) + H2O (g)

Substance

Mass/g

Water

54

Amount of substance/mol

Carbon dioxide

Total no. of O atoms 3.16 · 1024

Ozone

Laws of chemical combination and chemical equations

2.5

23 Order the following amounts from the lowest to the highest according to mass:

18 We have the following information about a chemical reaction:

a) 0.25 mol of lead tetrachloride.

3 H2 + N2 8 2 NH3

b) 5 mol of water.

Mass of products/g

H2

N2

NH3

6.06

28.02

34.08

c) 1 mol of sulphuric acid.

24 Calculate how many atoms and molecules there are in the following samples: a) 18 g of water.

a) Calculate the mass of ammonia that can be obtained if 7.878 g of hydrogen react completely.

b) 88 g of carbon dioxide.

b) Using the law of conservation of mass, calculate the mass of nitrogen required in the reaction based on the previous data.

104

3 Cl2 + 2 Fe 8 2 FeCl3

Calculate the mass of iron which will react and the mass of FeCl3 which forms.

c) 3 HCl + Al(OH)3 8 AlCl3 + 3 H2O

Mass of reagents/g

21 For the reaction of chlorine gas with iron:

c) 81 g of aluminium.

anayaeducacion.es Check the ‘Let’s study’ and ‘Learn by playing’ sections in the resource bank.

Unit

25 Silicon can be obtained from the reaction of SiO2 with coke (C) in an electric oven.

For this reason, fuels with lower carbon numbers are preferably being used. a) Balance the combustion reactions of methane (CH4), ethane (C2H6), propane (C3H8) and butane (C4H10):

a) Balance the chemical reaction:: + ___CO ___SiO ? ? 8 ___Si ? ?

2 + ___C 2 b) Which carbon mass reacts with 1 kg of SiO2?

I. ___CH ? ? 2 8 ___CO ? ? 2O 4 +___O 2 + ___H

Data: M (Si) = 28,09 g/mol; M (O) = 16 g/mol; M (C) = 12 g/mol.

II. ___C ? 2H6 + ___O ? 2 8 ___CO ? ? 2O 2 + ___H III. ___C ? 3H8 + ___O ? 2 8 ___CO ? ? 2O 2 + ___H

26 If we make potassium (K) react with water (H2O), potassium hydroxide (KOH) is formed and hydrogen gas (H2) is released.

IV. ___C ? 4H10 + ___O ? 2 8 ___CO ? ? 2O 2 + ___H b) One criterion to establish which one of the previous fuels is most polluting is to compare the amount of carbon dioxide released in the combustion of one mole of each one of them. Fill in the table with this information:

a) Write the balanced chemical equation. b) Calculate which mass of hydrogen gas is released in the previous reaction when 78 g of potassium react. c) If in the previous reaction, 20 g of potassium react with 9.21 g of water, what is the total amount of products obtained, in moles?

mole of CO2/mole of fuel methane ethane

Data: m (K) = 39 u; m (H) = 1 u.

27 Hydrochloric acid (HCl) combines with sodium hydroxide (NaOH) to give sodium chloride (NaCl) and water: a) Write and balance the chemical equation. b) To verify the law of conservation of mass is obeyed, calculate the mass of HCl needed for 103.5 g of NaOH to react completely. What masses of sodium chloride and water are produced?

28 An iron nail of 5 g is left out in the open. After some time, we see a part has oxidised, forming 5 g of diiron trioxide: a) What mass of iron has reacted? b) What mass of iron remains unreacted? Which percentage of the mass of the nail represents the part that has remained unreacted?

Chemistry and environment 29

Look up information on the destruction of the ozone layer and the anomalous greenhouse effect.

Draw up a comparative table regarding these two environmental problems.

30

What makes you say that? In the combustion of hydrocarbons, one of the reaction products is carbon dioxide. The greater the number of carbon atoms in the hydrocarbon, the greater the amount of carbon dioxide that is produced.

3

propane butane

31

The objective of the combustion of hydrocarbons is to transform chemical energy into another kind of energy. In order to quantify the energy obtained in each reaction, we use the power of combustion parameter (PC), which is expressed in kilojoules (unit of energy) per mole of fuel (kJ/mol). The table shows the PC values of the fuels in the previous activity: Fuel

PC/(kJ/mol)

CH4

890

C2H6

1 560

C3H8

2 220

C4H10

2 900

From these values, calculate, for each one, the amount of carbon dioxide released for each kilojoule of energy. Which fuel is most energyefficient? Which one releases less carbon dioxide into the atmosphere per kilojoule? Based on your results, what conclusions can you draw? Taking into consideration what you have learned, and goal 13.a, what fuel would you choose to produce energy?

What other sources of energy are in development to mitigate this fact? Check goal 7.2.

105

Building Blocks is an educational project of Anaya Educación for Secondary Education with the participation of: K. Chambers, Danny Latimer, R. Oakes, J. Roe, Hannah Peat, Karen Piper, Denise Suárez, Begoña Fuente Larrazabal, Sara Gascón Martín, Armando Caracheo, José Miguel Vílchez González, Ana María Morales Cas and José Gabriel Villalobos Galdeano.

The following people have worked on this book:

Editorial team: Manuel Gil, Margarita Marcos, María Ferrond, Sergio Gutiérrez and Denise Suárez Design, technical drawings and maps: Patricia G. Serrano, Juan Carlos Quignon, Julio Vázquez and Miguel Ángel Díaz-Rullo

Illustrations: M.a Carmen Fuente and Pablo Vázquez Layout: DiScript and Coral Muñoz CORRECTIONS: Anaya Corrections departament Graphic edition: Beatriz Gutiérrez Translation: Montero Language Services Proofreading and unit opening pages: Armando Caracheo Photographs: AEMET, AGE fotostock (Arco/R. Priemer, DAVID PARKER, Fine Art Images, Jim West,

JUNIORS BILDARCHIV, Mary Evans Picture Library, PROF PETER FOWLER/SC, SCIENCE PHOTO LIBRARY, Science Source, Sohns/imageBROKER, The Granger Collection, US DEPARTMENT OF ENERGY), Agencia EFE (MG), Alamy/Cordon Press (Historic Images, Panther Media GmbH, Roger Sedres, Science History Images), Archivo Anaya (Alcón, A. ; Santos, V.E.; Cosano, P.; Hernández Moya, B.; Martín, J.A.; Martínez, C.; Osuna, J.; Padura, S.; Peñuela Py, E.; Steel, M.; Sánchez, J.; Valls, R.), Dreamstime, Dres Esther Vázquez y Ugutz Unzueta del grupo de Nanobiotecnología de la Universidad Autónoma de Barcelona (UAB), Enresa, Getty images (Altayb, Bloomberg), Istock/Getty images, NASA (NASA’s Goddard Space Flight Center, NASA, ESA, and Z. Levy (STScI)), 123 RF y colaboradores.

Academic and Professional Orientation: created in conjunction with Fundación Bertelsmann.

Coordinator: Juan José Juárez Calvo. Expert collaborators: Sara Lozano Santiago, Belén Pérez Castro and Pilar Vázquez Hernández.

Commitment to Sustainable Development Goals Our publications contain carefully selected content, illustrations and language to comply with non-discrimination on the grounds of gender, culture or opinion.

Grupo Anaya considers social and environmental responsibility to be one of its fundamental values.

For this reason, we are committed to: · continually improving our contents and materials related to the environment. · reducing our carbon emissions. · using natural resources responsibly. · making sure that our activity has no negative consequences for endangered forests.

These commitments, among others, mean that 100% of the paper used in our books has the PEFC label.

Important information: The activities proposed in this book should be completed in a separate notebook or on sheets of paper, not in the book itself.

The links to webpages which appear in this book have been checked before printing. The publisher cannot be liable for any changes or modifications which occur after the date of publication.

© GRUPO ANAYA, S.A., 2021 - C/ Juan Ignacio Luca de Tena, 15 - 28027 Madrid.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the publishers.

e d

a c r ce

DEMO

física y química

3 ESO www.anayaeducacion.es

Building

Blocks

© GRUPO ANAYA, S.A., 2021 - C/ Juan Ignacio Luca de Tena, 15 - 28027 Madrid.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the publishers.

Índice El CONOCIMIENTO científico..................................... 4 1 ¿Qué es la ciencia? • 2 La física y la química • 3 Magnitudes físicas. Unidad y medidas • 4 Instrumentos de medida. Errores • 5 Múltiplos y submúltiplos • 6 El lenguaje de la ciencia • 7 Material de laboratorio. Normas de seguridad

1. EL ÁTOMO..................................................................................... 10 1 Primeras ideas sobre el átomo • 2 De la naturaleza eléctrica de la materia al primer modelo atómico • 3 De la radiactividad al modelo nuclear del átomo • 4 El núcleo del átomo • 5 La corteza del átomo y la tabla periódica • 6 Aplicaciones de los isótopos radiactivos

2. LAS SUSTANCIAS QUÍMICAS.......................................... 16 1 Sustancias simples y compuestas • 2 Los átomos se unen • 3 Enlace químico • 4 Moléculas y cristales • 5 Fórmulas químicas • 6 Aplicaciones industriales, biomédicas y tecnológicas

3. REACCIONES QUÍMICAS....................................................22 1 Cambios en la composición de las sustancias • 2 Ecuaciones químicas • 3 Leyes ponderales y ecuaciones químicas • 4 Química, medioambiente y sociedad

4. LAS FUERZAS Y SUS EFECTOS....................................26 1 Fuerzas • 2 Deformaciones • 3 Fuerzas cotidianas

5. LA NATURALEZA DE LAS FUERZAS.......................... 30 1 Fuerza gravitatoria • 2 Fuerza electrostática • 3 Fuerza magnética y electromagnetismo

6. CIRCUITOS...................................................................................36 1 Corriente eléctrica • 2 Circuito eléctrico • 3 Ley de ohm • 4 Dispositivos eléctricos • 5 Electrónica

7. FUENTES DE ENERGÍA....................................................... 42 1 Uso racional de la energía • 2 Centrales eléctricas • 3 Transporte y distribución de energía eléctrica • 4 Energía y potencia eléctricas • 5 Energía eléctrica en las viviendas

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Reacciones químicas

1 CAMBIOS EN LA COMPOSICIÓN DE LAS SUSTANCIAS 1.1 Cambios químicos

Los cambios en la materia que transforman unas sustancias en otras se denominan cambios químicos.

Una reacción química es todo proceso en el que una o más sustancias se transforman en otra u otras.

Las sustancias presentes antes del cambio son los reactivos y las que aparecen después, los productos de reacción.

Existen infinidad de tipos de reacciones, y podemos clasificarlas atendiendo a diferentes criterios. Por ejemplo, atendiendo al número de sustancias presentes en los reactivos y en los productos, hablamos de reacciones de descomposición (un reactivo da dos productos) o de síntesis (varios reactivos dan un producto).

Luz y energía en forma de calor

En ocasiones, no es fácil determinar si se está produciendo un cambio químico. El cuadro muestra algunas evidencias indicativas de una reacción química: cambios en las propiedades del medio en el que ocurre la reacción, como la formación de un precipitado, un burbujeo, etc.; intercambio de energía entre las sustancias y el entorno, como sucede en la combustión; cambios de color, etc.

Algunas evidencias de una reacción química

Sustancia poco soluble

Sustancia gaseosa

1.2 Teoría de las colisiones Según la teoría de Dalton, una reacción consiste en una reordenación de átomos debido a que las partículas chocan unas con otras y como consecuencia se rompen los enlaces que unen los átomos de los reactivos y se forman enlaces nuevos. Para ello, se tienen que cumplir las condiciones de que los choques deben tener la energía suficiente y su orientación debe ser la adecuada.

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Sustancia de otro color

1.3 Factores que afectan a la velocidad de reacción

Temperatura y velocidad de reacción

Existen reacciones extremadamente rápidas, como las explosiones, y otras muy lentas, como la oxidación del hierro.

Unidad 3

La velocidad de una reacción química se define como la variación de la cantidad de los productos obtenidos (o de los reactivos que desaparecen) por unidad de tiempo.

Los factores que influyen en esta velocidad son la temperatura, que aumenta la velocidad de las partículas y su energía, y la concentración de los reactivos, ya que favorece una mayor probabilidad de colisiones.

Las reacciones de descomposición de los alimentos son más rápidas a temperatura ambiente (derecha) que en cámaras refrigeradas (izquierda).

2 ECUACIONES QUÍMICAS Una ecuación química es la representación simbólica de una reacción química que contiene información cuantitativa y cualitativa. Se compone de las fórmulas químicas de los reactivos separadas por el signo «+», el símbolo del cambio químico (8) y las fórmulas de los productos separadas también por el signo «+». Además, aparecen los coeficientes estequiométricos, que indican el número de partículas de cada sustancia. Y finalmente, para poder leer la información cuantitativa de la ecuación química esta debe estar ajustada, es decir, que el número de átomos de cada elemento que interviene en la reacción debe ser igual en los reactivos que en los productos.

Ajustamos la reacción de sulfuro de hierro(II) con oxígeno para dar óxido de hierro(III) y dióxido de azufre. Sin alterar las fórmulas químicas de reactivos y productos, seguimos estos pasos:

Comprende, piensa, aplica...

1 Escribe

la ecuación química que corresponde a la siguiente descripción: «Dos moléculas de dihidrógeno se combinan con una molécula de dinitrógeno y dan lugar a dos moléculas de amoníaco».

REACTIVOS

Sulfuro de hierro(II)

PRODUCTOS

Oxígeno

Óxido de hierro(III)

Dióxido de azufre

Después, se ajustan las sustancias simples, finalizando con el H2 y el O2. Para ello, contamos el número de átomos en los productos y ajustamos en los reactivos:

Se eligen los elementos que aparecen solo en un reactivo y en un producto y se ajustan sus coeficientes estequiométricos.

Primero, los metales y, luego, los no metales:

Así, los coeficientes estequiométricos son: 2 FeS + O2 8 Fe2O3 + SO2

2 FeS + O2 8 Fe2O3 + 2 SO2

4 FeS + 7 O2 8 2 Fe2O3 + 4 SO2

1 Ò 4 = 4 átomos de S 2 Ò 7 = 14 átomos de O

UC TO S OD

1 Ò 4 = 4 átomos de Fe

PR

RE

AC T

IVO

S

Para evitar que aparezcan coeficientes fraccionarios, multiplicamos todos los 7 coeficientes por el denominador de la fracción, 2 · (2 FeS + 2 O2 8 Fe2O3 + 2 SO2) aunque ambas expresiones son válidas:

2 FeS + 7 O2 8 Fe2O3 + 2 SO2 2

2 Ò 2 = 4 átomos de Fe 1 Ò 4 = 4 átomos de S 3 Ò 2 + 2 Ò 4 = 14 átomos de O

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3 LEYES PONDERALES Y ECUACIONES QUÍMICAS

Comprende, piensa, aplica...

Entorno a 1804, se dieron a conocer las denominadas leyes ponderales, que establecían relaciones entre las masas de los reactivos y los productos. Ya en 1789, el científico francés A. Lavoisier llegó a la conclusión de que en una reacción química ni se destruye ni se genera masa, sino que solo se produce una transformación de sustancias; es decir, la suma de las masas de los reactivos es igual a la suma de las masas de los productos. A esta conclusión se la denomina ley de conservación de la masa.

2 Sabiendo que las masas atómicas

Además, el científico J. L. Proust estableció la ley de las proporciones definidas, según la cual en una reacción química, la proporción entre las masas de los reactivos y los productos es fija e independiente de la cantidad que reaccione.

3 En las reacciones de combustión

Esta ley empírica se explica teniendo en cuenta que la composición de cada sustancia, expresada en su fórmula química, es constante; que la masa atómica promedio se obtiene a partir de la masa de los elementos que la componen, y que el número de entidades elementales de cada sustancia que interviene en la reacción es constante y se representa mediante los coeficientes estequiométricos.

promedio del hidrógeno (1 u) y del nitrógeno (14 u), ¿se cumple la ley de conservación de la masa en la formación de amoníaco (NH3) a partir de dihidrógeno (H2) y dinitrógeno (N2)? de madera en una chimenea, al finalizar, se obtienen cenizas. La masa de cenizas es inferior a la masa de madera quemada. ¿Por qué ocurre esto? ¿Se cumple la ley de

En el ejemplo siguiente comprobaremos la relación que existe entre la ley de conservación de la masa y la información que se obtiene a partir de una ecuación química.

El amoníaco (NH3) se combina con oxígeno (O2) para producir monóxido de nitrógeno (NO) y agua (H2O).

4 NH3 + 5 O2 8 4 NO + 6 H2O

Masa atómica

N.º átomos en reactivos

N.º átomos en productos

N

14 u

4·1=4

N

4·1=4

H

1u

4 · 3 = 12

H

6 · 2 =12

O

16 u

5 · 2 = 10

O

4 · 1 + 6 · 1 = 10

REACTIVOS

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Comprobamos que la ecuación química está ajustada.

Añadimos el dato de la masa atómica promedio, que será necesario más adelante.

PRODUCTOS

NH3

O2

NO

H2O

14 + 3 · 1 = 17 u

2 · 16 = 32 u

14 + 16 = 30 u

2 · 1 + 16 = 18 u

17 u · 4 = 68 u

32 u · 5 = 160 u

30 u · 4 = 120 u

18 u · 6 = 108 u

68 u + 160 u = 228 u 24

Ecuación química ajustada.

120 u + 108 u = 228 u

Calculamos la masa molecular a partir de la masa atómica promedio.

Calculamos la masa que hay de cada sustancia en la reación a partir de la masa de su molécula y del coeficiente estequiométrico.

Comprobamos que se cumple la ley de conservación de la masa.

Unidad 3

MEDIOAMBIENTE Y SOCIEDAD

4 QUÍMICA, 4.1 Industria química

La química tiene un gran impacto en la calidad de la vida de las personas, ya que aporta nuevas sustancias con todo tipo de aplicaciones y ayuda a solucionar problemas ambientales.

Uno de los objetivos principales de la industria es la transformación de materias primas en infinidad de productos elaborados o facetas de la vida cotidiana, como la potabilización de aguas, nuevos materiales, dispositivos electrónicos, carrocerías de coches y un largo etcétera.

4.2 Problemas ambientales Pero todo lo anterior produce problemas que tienen lugar en la atmósfera como resultado de la emisión de gases en reacciones químicas como: • La lluvia ácida. Se origina en zonas industriales, que emiten a la atmósfera gases como los óxidos de azufre y nitrógeno, que reaccionan con el vapor de agua atmosférico generando ácidos corrosivos como el sulfúrico (H2SO4) y el nítrico (HNO3). Posteriormente, precipita en forma de lluvia ácida y sus efectos son muy negativos para la fauna y la flora, así como para los edificios históricos, etc.

• El efecto invernadero anómalo. Se produce porque el aumento de dióxido de carbono, CO2, en la atmósfera hace que la temperatura aumente. En las últimas décadas, la cantidad de este gas ha aumentado de forma notable por las reacciones de combustión del carbón, el petróleo, etc. Este gas retiene la radiación infrarroja que calienta la atmósfera, lo que provoca huracanes, ciclones, etc.

Efecto de la lluvia ácida en un bosque.

• El ozono. Está formado por tres átomos de oxígeno, O3, y forma una capa de unos 60 km de altura sobre el nivel del mar en la estratosfera.

El ozono absorbe una parte de la radiación solar que es perjudicial para la salud, la radiación ultravioleta. Pero en las últimas décadas se ha detectado un agujero en dicha capa, provocado por gases procedentes de la actividad humana, y, en consecuencia, la legislación promovida por acuerdos internacionales ha limitado mucho dichas emisiones y se ha conseguido revertir considerablemente ese problema.

Evolución de la capa de ozono en el año 2019.

El efecto invernadero

Comprende, piensa, aplica...

Sol

conservación de la masa? Razona tu respuesta.

Parte de la radiación solar es reflejada por la Tierra y la atmósfera

La mayor parte de la radiación infrarroja es absorbida por los gases de efecto invernadero

Atmósfera Tierra

Parte de la radiación solar es absorbida por la superficie terrestre y la calienta

La superficie terrestre emite radiación infrarroja

4 El desarrollo de la industria química

está acompañado de una alta contaminación del agua, el aire y el suelo. Desde hace tiempo, muchas empresas han tratado de reducir este efecto tan negativo, pero es muy difícil por el alto coste económico y la complicada adaptación de las infraestructuras. Busca información sobre una empresa que haya logrado adaptarse a los objetivos establecidos por la ONU. ¿Qué medidas han 25