SCIENCE 5. UNIT 6. MATTER AND ENERGY

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UNIT 6. MATTER AND ENERGY.

SCIENCE 5.

CONTENTS: 1.– Matter: .- General properties: mass, volumen. .- Specific properties: density, hardness, solubility...

2.a.- States of matter: solid, liquid, gas.

2.b.– Phase transition: evaporation, condensation...

3.- Pure substances and mixtures (separation processes).

4.- Chemical reactions: oxidation, combustion, fermentation 5.- Forces produce deformation and movement. Gravity.

6.– Velocity.

C.E.I.P. SANTA ANA (Madridejos)

MATTER is anything that has a mass and volume and occupies a space .

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1.– MATTER: is anything that has a mass (it is possible to be weighted) and occupies a space (volume).

GENERAL PROPERTIES: a.- Mass: is the amount of matter in an object.

We can measure the mass with a scale.

The unit of mass is the gram (g.) .

1 kg = 1000 g.

1 tonne = 1000 kg.

We can measure the mass with a scale.

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b.- Volume: is the space that a substance or body occupies or contains. We can measure the volume of a solid putting into a graduated container with a liquid, and watching the increasing of the liquid level.

The unit of volume is the litre (l.)

1 cm3 = 1000 ml = 1 l.

1000 litres = 1 m3 MASS: is the amount of matter in an object.

VOLUME: is the space that a substance or body occupies or contains.

3 We can measure the volume with a graduated container.

SPECIFIC PROPERTIES: .– Density: is the mass of an object divided by its volume.

There are substances with a great mass in a small volumen (iron), we can say that iron is very dense, but there are others like air, oil, wood.… that are less dense.

The unit of density is kg/m3 or g/cm3. (m) Volume (V)

MASS DENSITY = ———— VOLUME

d = _Mass

.– Buoyancy: is the upward force exerted by a fluid that opposes the weight of an immersed object Wood floats because is less dense than water.

Liquids with a different density 4

.- Hardness: is the ressistance of a substance to being scratched. .– Solubility: is the ability for a substance (the solute), to dissolve in a solvent. Salted water is a solution, it is a mixture of salt (the solute) and water (the solvent).

Weight

.– Thermal conductivity: is the property of a material to conduct heat. If you put a pan on the fire, and later you touch it, you could be hurt because of the heat from the fire is transmitted to you by the metal.

USEFUL WORDS: .– matter .– mass .– buoyancy .– hardness .– thermal conductivity

.– volume .– solubility

.– density 5

Buoyancy 6

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2.1.– STATE OF MATTER: We can find matter in three types of states:

C.E.I.P. SANTA ANA (Madridejos)

STATE OF MATTER: solids, liquids and gases.

a.- Solids have a fixed volume and shape, with particles close together and fixed into place. b.- Liquids have a fixed volume, but its shape are adapted to the containers. Particles are still close together but move freely.

c.- Gases have variable volume and shape.

They adapt to the container. Particles are not close together and move freely.

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2.2.- PHASE TRANSITIONS: Phase transitions describe changes between solids, liquids and gases. These changes depend on the increasing or decreasing of temperature.

Temperature is the numerical level of hot or cold of a thing or substance.

The unit of temperature is the degree ºC, or ºF.

TEMPERATURE INCREASES

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.- Temperature increases: .-Melting: changing of a substance from solid to liquid. Melting point of water is 0ºC .- Evaporation: changing from the surface of a liquid into a gas. Boiling is when the vaporization occurs within the entire mass of the liquid.

Boiling point of water is 100ºC .- Temperature decreases: .- Condensation: is the change of a substance from a gas into a liquid.

Water vapour condenses into liquid after making contact with a cold surface (eg. a cold bottle). .- Freezing: is the change from a liquid into a solid when the temperature is below its freezing point.

Water becomes ice when temperature is 0ºC.

TEMPERATURE DECREASES

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11 13

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Solid: ice

Liquid: water

Gas: clouds

3.– PURE SUBSTANCES AND MIXTURES: We can find substances in nature in different ways: .– Pure substances are substances formed by only one type of matter (eg. Oxygen, gold, water...). .– Mixtures are subtances formed by two or more types of matter together (eg. salted water, granite, foods... ) Pure substance: gold.

USEFUL WORDS: .– solid .– liquid .– evaporation .– boiling point

.– gas .– freezing

.– temperature .– condensation

Mixture: chocolate and milk.

.– degree .– mixture

.– melting point .– pure substance

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3.1.– MIXTURES: TYPES. We can find two types of mixtures:

C.E.I.P. SANTA ANA (Madridejos)

We can find pure substances and mixtures.

There are heterogeneous mixtures and homogeneous mixtures.

Heterogeneous mixture: oil and water

oil water

Homogeneous mixture: salted water

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Heterogeneous mixture: oil and water

a.– Heterogeneous mixtures: we can see the different types of matter because they don’t have an uniform composition ( e.g.: a rock)

b.– Homogeneous mixtures: we can’t see the different types of matter because they have an uniform composition (e.g.: salted water, air…)

3.2.- MIXTURES: SEPARATION PROCESSES.

There are different processes to separate mixtures like:

filtration, evaporation, magnetic separation...

15 We use filtration to make coffee.

1.- Filtration: is a method of separating a solid from a liquid, to remove solid particles (e.g.: mixture of sand and water).

16 Evaporation to extract salt from the sea.

2.- Evaporation: is a method to heat the mixture until the solvent evaporates (turns into gas) leaving behind the solid residue (e.g.: extraction of salt from seawater)

4.- CHEMICAL REACTIONS. The most important chemical reactions are:

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Oxidation of iron

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Magnetic separation is used to separate iron pieces from sand.

3.- Magnetic separation is a method for separating mixtures when one of the solid has magnetic properties (e.g.: mixture of iron and another solid).

A chemical reaction is a process that transforms some chemical substances into other different substances called products.

Types: oxidation, combustión & fermentation

Oxidation of fruit.

4.1.- Oxidation is a chemical reaction in which a substance combines with oxygen. Example: an object made of iron combines with the oxygen from the air (in a wet environment) so it will get rusted. .– heterogeneous mixture .– magnetic separation

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.– homogeneous mixture .– chemical reaction

.– filtration .– oxidation

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Combustion

4.2.– Combustion is a very quick oxidation process, between a fuel (wood, paper…) and oxygen. Every combustion produces heat and light.

USEFUL WORDS: .– evaporation .– fermentation .– combustión

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C.E.I.P. SANTA ANA (Madridejos)

4.3.– Fermentation is a process that converts sugar to other

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substances like gases (CO2, alcohol… It is made by yeast, bacteria... It is used to produce alcoholic drinks (beer, wine…) and dairy pruducts (yogourt), bread...

A force can change the position or movement of an object, or makes a deformation on it.

5.– FORCES PRODUCE DEFORMATIONS AND MOVEMENT. 5.1.– FORCE: There are forces that produce movement and others produce deformations on objects.

Beer and bread, are examples of fermentation in food.

A.– Forces that make deformations: When a force acts on an object, it can produce some deformations on its shape. So we divide objects in: 1.– Elastic objects change their shape only when the force is acting. (e.g.: , spring, rubber…).

Elastic objects.

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2.– Plastic objects change their shape, and do not get the previous shape after the force has finished (e.g.: plasticine, clay…)

Plastic objects.

3.– Rigid objects do not change their shape, the force breaks them (e.g.: mirror, eggs…)

There are three types of objects depending on the deformation by forces: Elastic, plastic and rigid.

Rigid objects

B.– Forces that produce changes in position or movement: 1.– Contact forces: when an object produce a force on another object by contact (touching the other object).

2.– Non-contact forces: when an object interacts with another object without touching it (magnetism, gravity).

Gravity is the force of attraction between every object and the Earth. (e.g.: an object falling down to the floor).

In the 17th century, Sir Isaac Newton discovered gravity.

Contact force: people pushing a car.

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Gravity is the force of attraction between every object and the Earth.

USEFUL WORDS: .– elastic objects .– rigid objects .– non-contact forces

.– plastic objects .– contact forces .– gravity

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Isaac Newton

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C.E.I.P. SANTA ANA (Madridejos)

Gravity attracts objects to the centre of the Earth, from every place.

The force of attraction depends on the mass of the Earth and the object’s mass.

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The quantity of this force is called weight.

So the weight of an object is different if the object is placed on the surface of the Earth than if the same objectd is placed on the surface of the Moon.

28 Gravity attracts objects from everyplace.

5.-VELOCITY or SPEED: There are lots of forces that produce movement on objects (a car engine moves a car, a man moves a bicycle, the raquet makes a force that moves the tennis ball…).

So, forces move objects a distance during a time.

The relation between a distance (space) and the time is called ―velocity‖ or ―speed‖.

The woman moves the bike.

The car engine moves the car.

Imagine we apply a force to a toy car, and it moves 1 metre during 1 second.

Its velocity (or speed) is 1 metre per second.

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Velocity = Distance Time V = 1 metre = 1m/s 1 second

1 metre

We can measure velocity (or speed) in different units.

The most common ones are:

Metres per second m/s Kilometres per hour km/h

When an object is moved: Velocity is the distance, divided by the time it spends.

Velocity = Distance Time 30

Imagine a car goes from Madrid to Córdoba. The distance between these two cities is 400 km. The car spends 4 hours during the trip.

Let’s calculate its speed.

Remember: Velocity is the distance divided by the time.

Velocity = 400 kilometres 4 hours USEFUL WORDS: .– gravity .– weight .– distance .– time

=

100 km/h

.– velocity/speed 31

Trip from Madrid to Córdoba 400 km