O Level Chemistry Notes

1

(ÿjjovel CHEMISTRY O Level NOTES (CIE SYLLABUS CODE 5070)

2016 – 18 Edition

Umar Zaman Khattak M.Sc Chemistry, B.Ed

Visiting teacher at: Garrison Academy for Cambridge Studies

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Title

O-Level Chemistry Teacher’s Notes

Author

Umar Zaman Khattak Cell: +92 3004846717 Email: umarzamankhattak4846717@gmail.com

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PREFACE This is a comprehensive and carefully balanced compilation of all the relevant topics that need to be essentially covered and understood by any O Level candidate who wishes to ace his Chemistry paper. We have managed to adopt a purely focused and goal oriented approach in this context that would enable students not only to grasp the content but also assist them in analysing and evaluating individual components.

Umar Zaman Khattak Cell: +92 300 4846717 Email: umarzamankhattak4846717@gmail.com

6

Contents Unit Topic 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Separation or Purification or Experimental Techniques Kinetic Particle Theory Atomic Structure Elements, Compounds & Mixtures Periodic Table Chemical Bonding Moles & Calculations Electrolysis Rate of Reaction: Energy Changes Reversible Reactions Redox Reactions Acid Base-Salt Metals Air and Atmosphere Organic Chemistry Macro Molecules (Polymers) CIE Syllabus for the Exams of 2016 onwards

Page 7 16 26 31 38 47 58 77 89 98 107 110 115 124 132 145 167 174

CIE O Level Chemistry Notes

7

Unit 1: Experimental Chemistry

Unit 1: Separation or Purification or experimental Techniques 1) 2) 3) 4) 5) 6)

Filtration Crystallization Simple Distillation Fractional Distillation Sublimation Chromatography

1)

F titration

Filtration:

solvent

Principle: Separation of an insoluble solid from a solution or solvent is known as filtration.

filler paper

Apparatus:

filler funnel

ÂĽ

NOTE: Limitation: The process of Filtration cannot separate a soluble solid from a solution.

Importance: Purification of river water to make it drinkable.

(insoluble solid)

clamp

fill rate (soluble solid dissolved in solvent)

r RIVER

residue

Sedimentation

Fine Filter Bed

Carbon Charcoal

To remove big

Water is allowed to

To remove fine solid

To remove taste,

particles

stay to settle denser

particles

color and smell

SCREENING

particles

V1 Sludge To Town

To kill Bacteria Valve Pump

Water tank

Chlorination

NOTE:

'or

y

Sludge: it is a rich plants nutrient, because it contains large amount of urea, therefore it is very important for healthy growth of plants.

Unit 1: Experimental Chemistry

8

CIE O Level Chemistry Notes

Crystallization: Principle:

Separation of a soluble solid from a solution is called crystallization.

Crystal:

The definite geometrical shape of a solid is called its crystal. The process of making crystals is called crystallization.

Crystallization by

Hot method

Cold Method

Cold Method e.g. prepare pure crystals of copper sulphate (CuSO4) 1.

2.

3.

4.

Prepare a saturated solution of CuSo4.

Filter the solution.

Place the filtrate in a cold atmosphere, after many hours few large size crystals will form.

Filter to separate crystal, wash it with distill water and then dry it between the folds of filter paper.

Note: • •

It is a slow process but very suitable method for making large size crystals.

It is a very suitable method for making heat unstable crystals.

Hot Method e.g. Prepare pure crystals of copper Sulphate (CuSO4) 1. Prepare a saturated solution of CuSo4.

2. Filter the solution.

3. Place the filtrate on flame in evaporating dish until crystallizations, cool it, filter it and wash it with distill water and then dry it between folds of filter paper.

NOTE: Don’t heat the filtrate till dryness because: 1) The crystals may decompose, if it is heat unstable.

2) Water of crystallization may loss if present.

3) A powdered compound is obtained instead of crystals.

Effect of Excess Heat on Crystals Example: CuSO4 .5H2O Hydrated Copper Sulphate (Blue Crystals)

Importance:

Heat –5H2O

CuSO4

©©IT ©

Heat

Anhydrous Copper Sulphate

(White Crystals)

Desalination of Sea Water (Removal of salt from sea water)

CuO + SO2 Copper Oxide (Black Solid)

CIE O Level Chemistry Notes

3)

9

Unit 1: Experimental Chemistry

Simple Distillation: Separation of pure solvent from soluble solid solute.

Principle: Apparatus

Thermometer water out

1

'L

Leibeg condensar or water condensar

Delivery Tube Boiling Flask

water in ,*A

— Receiver

ÂŤ Anti Bumping Stones

ft

Heat

beaker

7

J

nr

Distillate

1. Order of working: First boiling & then condensing.

2. Anti bumping stones are added to avoid the splashing or bumping of solution at boiling point to prevent large bubbles to form and to allow small bubbles to form at boiling point.

3. The bulb of the thermometer should be parallel to the mouth of the delivery tube to measure an accurate boiling point.

4. In water condenser, the water should enter from the lower bottom side to ensure good condensation because when water move from bottom to top then it completely fill the condenser, stay longer & the vapours which are just going to escape from the condenser will receive fresh cold water due to which their condensation will also occur.

5. Top of the receiver flask should be open to allow trap air and uncondense vapour to escape.

&

Importance: 1. To make distill water.

2. Desalination.

NOTE: Uses of distill water:

1) As electrolyte in car batteries.

2) It is used in pharmacy to make medicines.

3) For making solutions of exact concentration in Laboratory for experiments.

Š

CIE O Level Chemistry Notes

4)

10

Unit 1: Experimental Chemistry

Fractional Distillation:

Principle:

Separation of miscible (dissolved) liquids from each other according to the difference in their boiling points.

Apparatus: Function of fractionating column:

Thermometer

It is packed with glass beads which increases its surface area, its function is to condense back the vapors of un-boiled liquid & allow the vapors of the liquid whose boiling point has been reached to pass through.

Note:

Waterout " •i

il' ™

Fractionating Coloum Pacÿec* w'th glass beads

Condeser

1) The liquid with the lowest boiling point separate first and so on Round Bottom and so forth.

Water in Flask 2) When bp point of one particular liquid is reached then reading on thermometer becomes 0 constant until it is distilled over. When one Bunsen Burner liquid is distilled over then reading on thermometer starts to rise and also droplets in the receiver flask stops for a while, in this way the student comes to know that one liquid is completely collected in the receiver flask.

a

£

1

Importance: 1. Fractional distillation of petroleum.

2. Fractional distillation of liquid Air. (explanation is given in the unit of air and atmosphere)

TO

©

O

CIE O Level Chemistry Notes

11

Unit 1: Experimental Chemistry

Fractional Distillation of Liquid Petroleum: Cool (25*C) j

Refinery gases

Small molecules: * low boiling point * very volatile •flows easily •ignites easily

Bottled

gas

Gasoline (Petrol)

Maphtba

Kerosene

Diesel Oil

Heated crude oi

Fuel 0 I

feiiy> 11111

I

Residue

3

EH

Hot {350*C)

Large molecules: high boiling point •not very volatile •does not flow easily •does not ignite easily

&

%

oy

a

o.

CIE O Level Chemistry Notes

5)

12

Unit 1: Experimental Chemistry

Sublimation:

Principle: The direct conversion of a solid into a gas upon heating & a gas into a solid upon cooling without converting into a liquid form is known as sublimation. Such a substance would be known as sublime.

Solid

Heating (A)

Gas

Cooling (A) 1)

Iodine (I2)

4

Iodine (I2)

4

Cooling

(s)

Shiney Black 2)

> Element

(6)

Violet/ Purple vapor (A)

Ammonium chloride (NH4Q)

1

NH3 + HC1

(s) (cooling)

Carbon Dioxide (C02)

4

4

(g)

Compound

Violet/ Purple vapor

White 3)

4 (g)

Cooling

(C02) Dry ICE

;

heat

(g)

Gas Compound

(§)

Purification of impure Iodine

Shining Black Pure Iodine Crystals

05rs °C

r

Iodine Voilet or purple Vapours

rs gettyimages* Matt Meadows

impure Iodine Crystals

CIE O Level Chemistry Notes

13

Unit 1: Experimental Chemistry

Purification of Impure Ammonium chloride

Q*

Cotton plug

Inverted Funnel Clear Region Contains Colourless NH3 gas and HCI gas

s

Pine Shiny white Crytals of Solidfied

ammonium chloride

impure ammonium chloride

China Dish

1

I

;

I

ÂŽ>&

W o

<Ăż) o

Q

CIE O Level Chemistry Notes

6)

14

Unit 1: Experimental Chemistry

Chromatography: From a GREEK WORD

<

Chroma mean colour Graphy mean picture

Principle: Separation of Dyes/Colors from each other according to their solubility’s in the given solvent. e.g: Paper chromatography Apparatus:

Simple chromatography pil'CL' Ilf

WOfttl -

pin

—

paper

hi-aki-r

t

-

—

t

ink spot

s\ water

water

ink tint

Start

NOTE: i. ii.

iii. iv. v.

vi. vii.

The base line should be drawn with a lead pencil and not with ink pen as the ink pen itself is a mixture of dyes and would thus produce an inaccurate result.

The solvent rises up against the force of gravity through the pores of chromatogram and such movement is called capillary action. This type of chromatography is called Ascending Chromatography.

In descending chromatography, the solvent move downwards. It requires a longer chromatogram.

The mixture spot should be neither too big nor too small for better separation and for good result.

The solvent is the key factor for any type of chromatography, the solvent which produce maximum results/separation from the mixture spot will be the right choice O of solvent.

For chromatography to occur, all the dyes present in the mixture spot should be moderately soluble.

The dye which is the first to separate will be less soluble compared to that which will separate at the end, in the given solvent.

©

CIE O Level Chemistry Notes

ix.

15

Unit 1: Experimental Chemistry

Formula calculating RF Value

RF Value =

distance travelled by dye distance travelled by solvent front

Solvent front

T

new position of compound 2.1cm

origin

2.8cm

ÂŤ

2.1

R,'Z8

075

Application of Chromatography Or Advantages of Chromatography i. ii. iii.

iv.

v. vi.

It is used to check the purity of a substance; always a pure substance gives one spot on separation.

It is used to separate and identify piousness food additive or food colours which are not recommended by WHO. It is used to separate and identify even colourless compounds e.g. amino acids.

Protein is made up of colourless amino acids on separation they are not visible then a locating agent (e.g. Ninhydrin solution) is sprayed on chromatogram due to which different amino acids becomes visible with different colours which are then compared with the standard chart of amino acids hence identified.

This technique is used by forensic scientists to investigate crimes, from the incident place samples are collected which are then compared with the samples collected from suspects if matching occurs then they reach to conclusion.

It is also use to identify piousness insecticides which are not recommended by WHO. Various plants pigments (e.g. chlorophyll etc) can also by separated by this technique.

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