modul chemistry form 5

Modul Chemistry Form 5 [email protected]

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CHAPTER 1 : RATE OF REACTIONS A Rate of Reaction Learning Outcomes You should be able to :

state what rate of reaction is

identify observable changes to reactants or products for determining rate of reaction

determine the average rate of reaction

determine the rate of reaction at any given time from a graph

solve numerical problems involving average rate of reaction.

solve numerical problems involving rate of reaction at any given time.

Activity 1 : What is rate of reaction?

Rate of reaction is the ……………… at which reactants are converted into .………………….

in a chemical reaction.

The rate of reaction is a measurement of the change in the quantity of …………………. or

…………………………. against time.

Rate of reaction = Change in quantity of reactant /Product

Time taken

Activity 2 : Fast (F) or Slow (S) reactions? Write F for the fast reaction and S for the slow reaction.

1. Fading of dyes on a shirt under hot sun

6. Striking a match

2. A piece of paper turning yellow

7. Rusting of a water pipe

3. Frying an egg

8. Ripening of tomatoes

4. The weathering of limestone by acid rain

9. Digesting food

5. Burning of petrol in a car engine 10. Cooking a chicken using microwave oven

Activity 3 : Observable changes for measuring the rate of reaction The change in amount of reactant / product that can be measured by :

…………………………….. in the mass of reactant

…………………………….. in mass of product

…………………………….. in volume of gas released

…………………………….. of precipitate

Change in pH, temperature or electrical conductivity


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For each of the reactions below, write a chemical equation and state the observable change/changes can be used as selected quantities to measure the rate of reaction : Example 1 : The reaction between marble chip with hydrochloric acid to produce carbon dioxide gas and chloride salt. Chemical Equation : ………………………………………………………………………………. Changes :

(i) ………...………………………………………………………………………... (reactants)

(ii) …………………………………………………………………………………….(product)

Example 2 : Reaction between sodium thiosulphate solution with sulphuric acid to produce

yellow precipitate of sulphur, water , sulphur dioxide and sodium sulphate solution.

Chemical equation : ………………………………………………………………………………..

Change :

(i) …………………………………………………………………………………… (product)

Example 3 : Decomposition of hydrogen peroxide to produce water and oxygen gas.

Chemical equation : ………………………………………………………………………………..

Change :

(i) …………………………………………………………………………………… (product)

Activity 4 : Determine the Rate of Reaction. 4A 1. Two ways to measure the rate of reaction.

Average rate of reaction = Increase in the amount of product/decrease in the amount of reactant Time taken for the change to occur

2. a) Determination of average rate of reaction from the graph:

Time (s)

Volume of gas (cm3)

V3

V2

V1

60 120 240

180

V4 Overall Average rate of reaction Total Volume of gas collected = V4 Time taken for the reaction = 240 s Average rate of reaction = cm3s-1


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b) Instantaneous rate of reaction (Rate of reaction at any given time)

The rate of reaction at t sec

= gradient of the curve at t sec = a cm3s-1 b

c) Determining the rate of reaction at any given time

Average rate of reaction in the first two minutes = volume of gas collected in the first 120 seconds (cm3) time taken (s) = cm3s-1

Average rate of reaction in the third minute Volume of gas collected in the first 180 sec = V3 Volume of gas collected in the first 120 sec = V2 Volume of gas collected in the third minute = ____________ cm3

Time taken for the reaction = 180 – 120 = _______ s

Average rate of reaction in the third minute = m3s-1

Time (s)

Volume of gas (cm3)

V1

30 120

160

V2

Instantaneous rate of reaction / the rate of reaction at 120 sec = gradient of the curve at 120 sec = cm3s-1


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4B 1. In the experiment to determine the rate of reaction between marble chips and hydrochloric acid, the

volume of oxygen gas collected at intervals of 0.5 minutes is recorded in the table below :

Time (min) 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Volume of oxygen gas(cm3)

0.00 27.00 46.00 59.00 70.00 79.00 86.00 92.00 95.00 95.00 95.00

Plot a graph of the volume of gas collected against time.

30

40

50

10

60

70

80

90

100

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Graph of volume of oxygen gas liberated against time

Volume of gas (cm3)

Time (min)

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0


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2. Based on the graph plotted, determine

(i) the average rate of reaction in the first 3 minutes

(ii) the average rate of reaction in the third minutes

(iii) the overall average rate of reaction

(iv) the instantaneous rate of reaction at 1 minute


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Activity 5 1. The following figure shows the graph of carbon dioxide, CO2 gas produced when an excess of calcium carbonate, CaCO3 reacts with 40 cm3 of 0.1 moldm-3 hydrochloric acid, HCl.

(a) Calculate the

(i) Average rate of reaction in the first 10 sec

(ii) Average rate of reaction in the first 30 sec

(iii) Overall average rate of reaction

(b) Based on the results in (a), how does the rate of reaction change with time. …………………………………………………………………………………………………………………….. (c) Explain your answer in part (b) with respect to the concentration of hydrochloric acid. …………………………………………………………………………………………………………………….. ……………………………………………………………………………………………………………………… 2. The following table shows the volume of a gas collected from an experiment.

Time (s) 0 30 60 120 150

Volume of gas (cm3) 0.00 17.00 29.00 36.00 36.00


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Calculate th average rate of reaction for (a) the first 60 seconds (b) the overall reaction 3. The decrease in mass of a reaction mixture is recorded in the following table.

Time (min) 0 1 2 3 4 5

Mass of reaction mixture (g) 2.90 1.90 1.25 0.75 0.40 0.10

(a) Draw a graph of mass of reaction mixture against time.

(b) Calculate the rate of reaction at the third minute.

B FACTORS AFFECTING THE RATE OF REACTION

Learning Outcomes

You should be able to :

design experiments to investigate factors affecting the rate of reaction.

give examples of reactions that are affected by size of reactant, concentration, temperature and catalyst.

explain how each factor affects the rate of reaction.

describe how factors affecting the rate of reaction are applied in daily life and in industrial processes.

solve problems involving factors affecting the rate of reaction.


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apply knowledge on factors affecting the rate of reaction in everyday activities.

Activity 6 : Factors affecting the rate of reaction. State five factors that affect the rate of reaction : (a) ……………………………………………. (b) …………………………………………..

(c) ……………………………………………. (d) …………………………………………..

(e) …………………………………………….

Activity 7 : Speeding up the Rates of reaction. The following changes may speed up the rate of a chemical reaction between an acid and magnesium. Put a tick in the box next to each one that will speed up the reaction (assume that there is initially an excess of acid) and state the specific factors that affect the reaction.

Statement of factors that affect the rate of reaction Specific factor

1. Heating the acid…………….

2. Shaking the flask………….

3. Using more-concentrated acid …………….

4. Using powdered metal, not metal ribbon ………….

5. Using twice the volume of acid ……………

6. Using a suitable catalyst …………….

7. Increasing the pressure …………..

8. Using larger flask ……………


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Activity 8 : Experiments to investigate the rate of reaction.

(i) Effect of size of reactants Aim : To investigate the effect of size of reactant in an experiment between marbles and hydrochloric acid on the rate of reaction. Equation : ……………………………………………………………………………………………..

The curve of experiment 2 is ……………………………. than experiment 1.

The rate of reaction of experiment 2 is ………………… than experiment 1

The smaller the size of reactants, the …………………………. the total surface area, the …………………………. the rate of reaction.

Volume of gas (cm3)

Time (s)

Experiment 1 : CaCO3 chips Experiment 2 : CaCO3 powder

Expt 1

Expt 2

Diagram of an experiment

(Refer the apparatus set-up for the experiment in page 7 Practical Book)


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(ii) Effect of concentration

Aim : To investigate the effect of concentration of sodium thiosulphate solution on the rate of reaction. Equation : …………………………………………………………………………………………………..

* The higher the concentration of the sodium thiosulphate solution, the …………………………… the time taken.

* 1/ t is ………………………………

The …………………. the concentration of sodium thiosulphate solution, the ………………………..the

time taken.

Concentration (moldm-3

) of sodium thiosulphate solution

Time (s)

Concentration (moldm-3

) of sodium thiosulphate solution

1/ time (s-1

)


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(iii) Effect of catalyst Aim : To investigate the effect of the presence of catalyst (Manganese (IV) oxide) on the rate of decomposition of hydrogen peroxide. Equation : …………………………………………………………………………………………………….. Draw the apparatus set-up for the experiment.

The curve of experiment 2 is ……………………………………………. than experiment 1.

The rate of reaction of experiment 2 is ………………………………….than experiment 1

The presence of catalyst, will …………………….................... the rate of reaction.

Volume of gas (cm3)

Time (s)

Experiment 1 : with catalyst Experiment 2 : without catalyst

Expt 1

Expt 2

Diagram of an experiment


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Activity 9 1. Activity 9 1.

(iv) Effect of temperature

Aim : To investigate the effect of temperature on the rate of reaction between sodium tiosulphate solution and sulphuric acid.

Equation : ………………………………………………………………………………………………………….

The higher the temperature, the ...………………………………. the time taken.

1/ time is ……………………………………………..

The ………………………….. the temperature, the …………………… the rate of reaction.

Temperature (oC)

Time (s)

Temperature (oC)

1 / time (s-1

)


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Activity 9 1 2. Meat cut into small pieces, have ……………………….. size compare to the meat cut into big

pieces. The ……………………… the size, the bigger the ……………………………………….

of the meat, hence the …………………………………… the rate of reaction.

3. State and briefly discuss two industrial processes that make use catalyst. [8 marks ] (i) Haber process is a chemical process to produce ……………………………… from nitrogen and

hydrogen gas. The equation of this process is …………………………………………………………...

The suitable condition of reaction are temperature : ………………………………………,

pressure : ………………………………….. and catalyst : ………………………………………………..

(ii) ……………………………… process is a chemical process of synthetisising sulphuric

acid. The equation of stage III for this process is……………………………………………..

The suitable condition of reaction are temperature : ………………………………………,

pressure : …………………………………….. and catalyst : ……………………………………………..

C COLLISION THEORY Learning Outcomes You should be able to :

relate reaction with energy produced by movement and effective collision of particles.

describe activation energy.

sketch and describe energy profile diagram

relate the frequency of effective collisions with the rate of reaction

relate the frequency of effective collisions with factors influencing the rate of reaction

describe how a certain factor affects the collision of particles in a reaction

[ Temperature in refrigerator is ……………………………. The lower temperature caused the bacteria

to be less ………………………. A little …………………… is released by the bacteria. The rate of the

food turns bad is …………………………. ] //

[ Temperature in kitchen cabinet is ………………………. The higher temperature caused the bacteria

to be ……………………reactive. A ………………………… toxic is released by the bacteria. The rate

of the food turns bad is ……………………………….]

Food store in a refrigerator lasts longer than food stored in a kitchen cabinet. Explain why. [4 marks]

One kilogram of meat, cut into big pieces, takes a longer time to cook compared to one kilogram of meat cut into small piece. Explain the above statement based on the size of the particles. [2 marks]


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Activity 10 Understandings the Collision Theory 1. What is collision theory ? A theory used to explain chemical reactions in terms of (i) …………………………………………………………………………………………………………………… (ii) ………………………………………………………………………………………………………………….. (iii) …………………………………………………………………………………………………………………. 2. The collision theory states that : (i) A chemical reaction occurs when the reactant particles ……………………….. each other. (ii) Not all collision result in the formation of ………………………………… (iii) A collision is ……………………………. only when the reactant particles have enough energy to overcome the ………………………………………………… of the reaction and when they collide in the proper orientation. 3. What is activation energy ?

The …………………………………… energy which the colliding reactant particles must have that can result a chemical reaction. 4. Energy profile diagram

In the energy profile diagram, the activation energy is the difference in the energy between the energy of the ……………………. and the energy shown by the peak of the curve.


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Activity 11 On the diagram shown below, identify (i) the activation energy, Ea and (ii) the activation energy in the presence of catalyst, Ea’

Activity 12 Collision theory and factors affecting the rate of reactions..

(i) Effect of total surface area

When the size of a fixed mass of solid reactant is

smaller, the _____________________ exposed to

collision with the particles of the other reactants is

_____________. Thus, the frequency of collision

among the reacting particles at the surface of the

solid reactant ____________ ___. This leads to an

_________________ in the frequency of effective

collision and hence, a _____________ rate of

reactions.

(ii) Effect of catalyst

The presence of a catalyst in a chemical reaction

allows the reaction to take place through an

alternative path which requires a ______________

in activation energy which can be shown in the

energy profile diagram. Thus, the colliding

particles are able to achieve the activation energy.

This means that the frequency of effective collision

__________________and hence, a

_______________ rate of reaction


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(iii) Effect of temperature

An increase in temperature will increase the

_________________ of the reacting particles. This

leads to the following two changes. Firstly, the

particles move _________________ and collide

more often with one another. Thus, the frequency

of collision is ________________ Secondly, more

colliding particles have ____________ energy

which are enough to overcome the activation

energy. Both these factors contribute to the

_________________ frequency of effective

collision and hence, a _____________ rate of

reaction

(iv) Effect of concentration and pressure

An increase in the concentration of the solution of

a reactant or in the pressure of gaseous reactants

will result in an __________________ in the rate

of reaction. Why? When the concentration of the

solution of a reactant increases, the

_________________ of particles per unit volume

of this reactant also _______________. With more

particles per unit

volume of the solution, the frequency of collisions

per unit time between the reacting particles

__________________. Thus, the frequency of

effective collision ________________ and hence,

the rate of reaction becomes

___________________.

Use the words below to fill in the blank boxes in the diagram Bigger surface area more particles cold hot slow less particles fast bigger size slow smaller size


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Activity 13 1. A group of pupils carried out three experiments to investigate the factors affecting the rate of a reaction. Table below shows information about the reactants and the temperature used in each experiment.

Experiment Reactants Temperature / oC

A Excess magnesium ribbons and 25 cm3 of 0.5 mol dm-3 hydrochloric acid

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B Excess magnesium ribbon and 25 cm3 of 0.5 mol dm-3 hydrochloric acid

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C Excess magnesium powder and 25 cm3 of 0.5 mol dm-3 hydrochloric acid

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Sketch a graph of these experiments on the same axes. [4 m] 2.. A student carried out three experiments to investigate the effects of the factors influencing the rate of reaction. Table below shows the results of the experiments.

Experiment I II III

Set-up of apparatus

Temperature / oC 30 40 40

Time taken for all the magnesium to dissolve / s

50

20

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Sketch the graphs for the volume of hydrogen gas against time for Experiments I, II and III using the same axes.

0.2 g magnesium

ribbon

Excess hydrochloric acid

Excess hydrochloric acid + copper(II) sulphate


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Activity 14 1 The table below shows the volume of hydrogen gas released when 50.00 cm3 of sulphuric acid

solution reacts with 5.0 g of granulated zinc.

Time/s 0 30 60 90 120 150 180 210

Volume of hydrogen gas released/cm3

0.00

80.00

125.00

165.00

190.00

210.00

210.00

210.00

(a) Write the chemical equation for the reaction between zinc and sulphuric acid.

……………………………………………………………………………………………...

[2 marks]

(b) Calculate the overall average rate of reaction of this experiment.

[1 mark] (c) (i) Draw the graph of the volume of hydrogen gas released against time.

[4 marks]

(ii) From the graph , calculate the rate of reaction at the 80th seconds.

[2 marks] (d) Instead of measuring the volume of hydrogen gas released, state another

method that can be used to calculate the rate of reaction in this experiment. ……………………………………………………………………………………………...

[ 1 mark]


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2.

Based on the table and graph above, compare the rate of reaction between :

(i) Experiment I and Experiment II (ii) Experiment II and Experiment III

Experiment I and Experiment II The rate of reaction of experiment II is …………………………… compared to experiment I. The

temperature of experiment II is ………………………. The higher the temperature, the

……………………… the kinetic energy of the particles. The ………………………………… between

hydrogen ions, H+ and calsium carbonate happened. The frequency of collision ……………………. The

frequency of ……………………………… collision also increases. Hence, the rate of reaction

is……………………………….

Experiment II and Experiment III

The rate of reaction of experiment III is …………………………… compared to experiment II. The total

surface area of the reactants in experiment III is …………………………………………..

The ………………………………… between hydrogen ions, H+ and calsium carbonate happened. The

frequency of collision ……………………………. The frequency of ……………………………… collision

also increases. Hence, the rate of reaction …………………


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CHAPTER 2 : CARBON COMPOUNDS

A UNDERSTANDING CARBON COMPOUND Learning Outcomes You should be able to:

State what carbon compound is,

State the carbon compounds can be classified into two groups, i.e. organic and inorganic,

State what organic compound is,

Gives examples of organic and inorganic carbon compounds,

State what a hydrocarbon is,

List the sources of hydrocarbon,

Identify the combustion products of organic carbon compounds

Activity 1 Fill in the blanks with the correct answer. 1 Carbon compounds are compounds that contain …………. as one of their constituent elements. 2 There are two groups of carbon compounds; ………………….. compounds and ………………..

compounds. 3 Carbon compounds that can be obtained from non-living things are classified as

………………..compounds. 4 Hydrocarbons are the simplest of all organic compounds. Hydrocarbon contains only two

elements, ……………………… and ………………………. 5 Organic compounds that contain carbon, hydrogen together with a few other elements such as

oxygen, nitrogen, phosphorus or halogens are called …………………………… 6 Hydrocarbons can be classified into two , ……………………….. and unsaturated hydrocarbons. 7. Hydrocarbons that contain only carbon-carbon single bond is called ……………………. 8 Hydrocarbons that contain at least one carbon-carbon double bond or carbon-carbon triple bond

is called …………… 9. Natural sources of hydrocarbons are ……………………, coal and natural gas. 10 Organic compounds burn in excess of oxygen gas to produce …………………….. and …………………….


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B ALKANES Learning Outcomes: You should be able to :

state what alkane is,

state what structural formula is,

deduce the molecular formulae of the first ten alkanes

Draw the structural formulae for the first ten straight-chain alkanes,

Deduce the general formula of alkanes

Name the first ten alkanes,

Relate changes in physical properties with increase in the number of carbon atoms in alkanes molecules

Explain the effect of the increase in number of carbon atoms in alkanes molecules on the molecules boiling points,

Describe complete and incomplete combustion of alkanes,

Describe the substitution reaction of alkanes,

Write chemical equations for combustion and substitution reaction of methane,

Describe how methane affects everyday life.

Activity 2 (a) Complete the table below:

Number of

Carbon

Structural formula Molecular formula

Name of alkane

Condition at room

temperature

1

CH4

Methane

Gas

2

3

4

5

6

7

C7H16

8

C8H18


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9

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b. Explain why on going down the alkane series, the melting and boiling point increase?

On going down the alkanes series, the ……………………………….. increases caused by the

increase in molecular size.

When the molecular size increases, the melting and boiling point ……………... This is

because the larger the molecular size, the stronger the ……………………….. forces of

attraction between the molecules. Thus more energy is needed to …………………. the

forces of attraction during melting or boiling.

c. Explain why alkanes are non-conductors of electricity.

Alkanes are covalent compounds made up of ………………………….

They don’t have ……… ..moving ions. Hence alkanes are non-conductors of electricity.

d Ethane and propene burn in excess of oxygen gas. Balance the chemical equation of the combustion of these hydrocarbons. (i) C2H6 (g) + O2 (g) CO2 (g) + H2O (l) (ii) C3H8 (g) + O2 (g) CO2 (g) + 4H2O (l) Activity 3 Complete the sentences with the correct word. 1 Carbon is placed in Group ……………..

2 It has ……………. electrons in its outer most shell.

3 An atom of carbon contributes ……………….. electrons to share with other atom of elements to

obtain the stable electron arrangement of inert gas elements.

4 Atoms in alkanes are bonded with ……………………… bond.

5 The first member in this group is the simplest compound called ……………….


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This smallest alkane can be found in natural gas and crude oil.

6 The general formula for the alkane family is ………………………..

7 Physical properties of alkanes

a ………………………………………………………………………

b ………………………………………………………………………

c ……………………………………………………………………….

d ……………………………………………………………………….

8 Alkanes are ……………… compound, they have no effect on blue or red litmus paper.

9 Alkanes burn readily in air or in excess oxygen to produce ………………and ………..

10 The alkanes burn with a ………………… flame if the combustion is not complete.

11 Alkanes undergo Substitution Reaction – atom of H is replaced with ……………….. or

…………………………… with the presence of sunlight or UV rays.

12 According to he IUPAC, the ending …………… indicates the compound is a member of

the alkane family.

Activity 4 a) Name the compound a, b, c, d, e, and f.

Methane (a) (b)

Substitution reaction (chlorination)

Excess chlorine Sunlight or heat

(c) (d) (e) (f)

Complete combustion with excess O2

Incomplete combustion (limited O2 )


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b) State the uses of methane in everyday life i ……………………………………………………………………………………..

ii …………………………………………………………………………………….

iii ……………………………………………………………………………………..

iv ……………………………………………………………………………………..

c) Explain how methane can cause fire in landfills and peat swamps

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………………………………………………………………………………………………

………………………………………………………………………………………….…….. C ALKENES Learning outcomes:

You should be able to:

state what alkene is,

deduce the molecular formulae of the first nine alkenes,

deduce the general formula of alkenes,

name the first nine alkenes,

draw the structural formulae for the first nine straight –chain alkenes,

relate changes in physical properties with increase in the number of carbon atoms in alkenes molecules,

explain the effects on boiling points of alkenes due to increase in the number of carbon atoms in alkenes molecules,

describe chemicals properties of alkenes,

compare and contrast alkanes with alkenes,

relate the reactivities of alkanes and alkenes to their chemicals bonds.

Generalise the characteristics of homologous series based on alkanes and alkenes

Activity 5 (a) Complete the table below:

Number of

Carbon

Structural formula Molecular formula

Name of alkane

Condition at room

temperature 2

3

4


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5

6

7

C7H14

8

9

10

(b) Fill in the blanks by choosing the suitable answer from the textbox below.

i) Alkenes are …………………. hydrocarbons.

ii) The names end with …………………… The general formula for alkenes is

……………………………

iii) Generally alkenes have …………………….. melting and boiling point but ………………..as

the number of carbon atoms per molecule increases.

iv) Alkenes have ……………… densities but increase as the number of carbon per atom

increases.

v) Alkenes are ……………… with water but are ………………………. in organic solvents.

vi) Alkenes …………………. conduct electricity.

vii) Alkenes burn with more ……………… flame compared with alkanes of the same number of

carbon atoms because the percentage of carbon by mass in alkenes is ……………………

viii) Compare to alkane, alkene is ………………… reactive, due to the presence of carbon-carbon

………….. bond.

ix) Alkane and alkene can be identified with a test by using ……………… water or

……………………………. solution. Alkene decolourises both reagent while alkane does not.

more , immiscible , soluble , sooty , higher , low, bromine, low, polymerization unsaturated, ene, CnH2n , double, acidified potassium manganate(VII) ,

increases, cannot


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x) Small alkene molecules undergo addition reaction with one another. Thousands of

alkene molecules link together to form a large molecule .

This reaction is called ……………………………………

Activity 6

(a) Give name for each alkene compounds below

(b) Construct the structural formula for:

(i) C5H10 (iv) 2-methylbut-2-ene

(ii) 2-chlorolpropene (v) 3-methylbutene

(iii) pent-2-ene (vi) hex-1,3-diene

CH3

Cl

CH3

Cl

iii vii

= H

iv viii

Cl

=

CH3

CH3

i v

ii vi


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Activity 7

Write the molecular formula or structural formula of the product for every reaction of propene below.

Activity 8

(a) Table below shows the reactions to compare the chemical properties of alkane and

alkene. Complete the table.

Reaction

Observation

Hexane Hexene

Reaction with oxygen Hexane burns with a yellow sooty flame

Reaction with bromine water

No visible change

Reaction with acidified potassium manganate(VII) solution

No visible change

Propene

limited O2 heat

excess O2, heat

b) a)

c)

Addition polymerization

H2O(g) 300 C,60 atm, H3PO4

d)

HCl (g)

e)

Cl2(aq)

f)

H2 / Ni .180o C

g)

acidified KMnO4 (aq)

h)


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(b) Calculate the percentage of carbon in

[ Relative atomic mass : H, 1 ; C, 12 ]

(i) hexane

(ii) hexene

Which compound can be a good fuel ? Explain .

(c) List down 4 similar physical properties of alkane and alkene.

(i) ………………………………………………………………………………….

(ii) ……………………………………………………………………………………

(iii) ……………………………………………………………………………………

(iv) ……………………………………………………………………………………

(d) Compare the chemical properties of alkene with alkane

Alkene Aspect Alkane

Sootiness of flame

Bromine water

Acidified KMnO4


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D ISOMERS Learning outcomes You should be able to:

Construct various structural formulae of a particular alkane and alkene.

Explain what isomerism is

Use IUPAC nomenclature to name isomers

Activity 9 a) Match column A with Column B

Column A

Column B

i) Phenomenon whereby two or more molecules are found to have the same molecular formula but different structural formula

Alkyl group

ii) The molecules that have the same numbers and types of atoms but differ in the arrangement of the atoms.

Ethene and Propene

iii) It is an alkane by dropping – ane from the name and replacing it with –yl

Isomers

iv) These alkenes do not exhibit isomerism. Isomerism

v) Isomerism in alkanes starts with …….. Butane

b) Draw the structural formula and give name to all isomers of (i) C4H8

(ii) C4H10

(iii) C5 H12


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E ALCOHOLS Learning outcomes You should be able to:

• state the general formula of alcohols, • identify the functional group of alcohols, • list the names and molecular formulae for the first four alcohols, • draw structural formulae for isomers of propanol (C3H7OH) and butanol (C4H9OH), • name isomers of propanol and butanol using IUPAC nomenclature, • describe the industrial production of ethanol. • ` describe the preparation of ethanol in the laboratory, • state the physical properties of ethanol, • predict the chemical properties for other members of alcohols, • explain with examples the uses of alcohol in everyday life, • explain the effects of the misuse and abuse of alcohols.

Activity 10 (a) Fill in the blanks by choosing the suitable answer from the text box below

i) Alcohol is one of the Homologue Series that has functional group of ……………..

ii) The general formula for alcohol is ……………………………….

iii) The melting point of alcohol is ……………….. than alkane and alkene due to the

presence of ……………………………….

iv) This is because the functional group forms hydrogen bonding that is …………..

than the bonds between molecules of alcohol.

v) Methanol, ethanol dan propanol dissolve in water. The solubility of other alcohols

decreases as the………………………… increases.

vi) Naming the alcohol compound is likely to ………….. C1 is numbered from the carbon that

nearest to the functional group..

vii) Alcohols are used as fuels, ………………., in medicine, in making ………………….

and as a main component in alcoholic drinks.

viii) Alcohol is a ……………………… compound.

Hydroxyl ; non-hydrocarbon , alkene , solvents, higher, cosmetics, stronger, molecular mass , -OH , CnH2n+1OH


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(b) Complete the table below.

i) Name :

ii) Name:

iii) Name

iv) structural formula Name : Propan-2-ol

v) structural formula Name : Butan-1-ol

vi) structural formula Name : Pentan-2,3-diol

( c) Draw the structural formula and give names to all isomers of

(i) propanol (C3H7OH)

(ii) butanol (C4H9OH)


33

Activity 11 (a) Summarize the physical properties of ethanol in the table below

Physical properties Description

Physical state at room temperature

Smell and colour

Solubility in water

Volatility

Boiling point

(b) Ethanol can be prepared in two ways, Fermentation and Hydration. In fermentation process, (i) What is the function of yeast? ………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

(ii) Write the chemical equation to show the fermentation process. …………………………………………………………………………… (iii) State the temperature, catalyst and other condition needed for fermentation process.

…………………………………………………………………………………….

……………………………………………………………………………………..

(iv) State the disadvantages of this process.

……………………………………………………………………………………..

……………………………………………………………………………………..

……………………………………………………………………………………………..

(c) Hydration process involves hydration of ethene. Ethene is obtained from the cracking of petroleum fractions.

(i) Write the chemical equation for hydration process.

…………………………………………………………………………………..

(ii) State the temperature, pressure and catalyst needed for hydration process.

……………………………………………………………………………………

……………………………………………………………………………………


34

Activity 12 a) Complete the table below

1 The Products of Combustion of ethanol

In excess oxygen:

In limited oxygen :

2 The products of Oxidation reaction of alcohol with acidified potassium dichromate(VI) solution or acidified potassium manganate (VII) solution

Oxidation of ethanol

Oxidation of propanol

3 Dehydration of alcohol.

Draw and label the set of apparatus to show the dehydration process of propanol.

b) State True or False for every statement below.

1 Ethanol is an alcoholic drinks

2 Ethanol acts as a depressant on central nervous system.

3 Alcoholic drinks only slow down physical activity, not affect mental activity.

4 Alcoholism create social problems for the family and society.

5 Methanol is a very toxic chemical and can cause permanent blindness when consumed

6 Alcohol is not addictive

7 Long- term excessive consumption of alcohol drinks can cause chronic liver disease and brain damage.

8 Because of alcohol is miscible with water, it cannot be used as a solvent in toiletries.

9 Alcohol is one of the raw materials in manufacture of explosive

10 Alcohol is an antiseptic


35

F CARBOXYLIC ACIDS Learning outcomes You should be able to :

state the general formula of carboxylic acids, identify the functional group of carboxylic acids, list the names and molecular formulae of the first four members of carboxylic acid, draw structural formulae of the first four members of carboxylic acid and name them using the IUPAC nomenclature, describe the preparation of ethanoic acid in the laboratory, state the physical properties of carboxylic acids, state the chemical reactions of ethanoic acids with other chemicals, predict the chemical properties for other members of carboxylic acid, explain with example the uses of carboxylic acids in everyday life

Activity 13 (a) Complete the diagram below.

Functional group :

CARBOXYLIC

ACIDS

Uses : a ……………………………… b ……………………………… c ……………………………… d ……………………………..

Ethanoic acid normally prepared by ………………… of an alcohol

names end with

‘……………..’ . Eg. ethanoic acid.

Physical properties a …………………………………………..

b …………………………………………..

c ……………………………………………

d …………………………………………..

e …………………………………………..

General formula:


36

(b) Draw the structural formula of

Methanoic acid

Ethanoic acid

Propanoic acid Butanoic acid

2-methylbutanoic acid

Methyl propanoic acid

( c) A carboxylic acid, X has an empirical formula CH2O. Experimental determination shows that it has a molar mass of about 59 g mol-1

(i) What is the general formula of carboxylic acid?

(ii) Calculate the molecular formula of X

[ Relative atomic mass : H, 1 ; C, 12 ; O, 16 ]

(iii) Draw the structural formula of X and give name.

Activity 14 a) Figure shows a series of conversion starting from ethene to ethyl ethanoate.

Based on the figure above, state Reaction I :………………………………………………………

Reaction II :………………………………………………………

I Ethene Ethanol Ethanoic acid II


37

b) Draw the set up of apparatus to prepare ethanoic acid .in laboratory Write the chemical reaction that involve. c) Write the observation of every test for ethanoic acid below.

Test Observation Inference

1 a. Ethanoic acid + metal carbonate

b. Gas released + lime water

2 a. Ethanoic acid + magnesium

b. Gas given off + lighted splinter

3 Ethanoic acid + copper (II)oxide

4 Glacial ethanoic acid + ethanol + concentrated sulphuric acid + heat Then the boiling contents are poured into a beaker half filled with water.

.


38

G ESTER Learning outcomes: You should be able to:

state the general formula of esters

identify the functional group of esters

List the names and molecular formulae of simple esters.

Draw structural formulae of simple esters and name them using the IUPAC nomenclature,

Describe the preparation of ester in the laboratory,

State the physical properties of ethyl ethanoate.

Predict the ester produced from the esterification reaction.

Write equations for the esterification reactions,

state the natural sources of ester, state the uses of ester in everyday life.

Activity 15 (a) Name the following esters and give the alcohols and carboxylic acids required to synthesise

the esters name.

b) Draw the structural formula for the compound form in the reaction between alchol and carboxylic acid below.

(i) methanol and propanoic acid

(ii) ethanol + butanoic acid

(iii) propan-1-ol + ethanoic acid

Formula Name Carboxylic acid Alcohol

Example :HCOOC2H5

Ethyl methanoate Methanoic acid Ethanol

a) CH3 COOCH3

b) CH3 COOC3H7

c) C2H5 COOCH3

d) C3 H7COOC3H7


39

Activity 16 (a) Complete the diagram below

b) Write the fruit flavour for each of the ester below

(i) n-pentyl ethanoate : ………………………….

(ii) Octyl ethanoate : ………………………….

(iii) Ethyl butanoate : ………………………….

ESTERS

Ester is a ………………….. organic compound

contain ………………, ………………… and …………………………….

The general formula is ……………………………

the functional group is –COO- or ……………. group

the name of an ester consists of two words. The first word originates from……………., the second is from the …………………….. All of them end with ‘ ………..’

product of an …………. reaction between a carboxylic acid and an alcohol.

The ……………of flowers and fruits is due to the presence of esters

uses of ester, a) …………………………..

b) …………………………..

c) ……………………………

d) ……………………………

Physical properties 1………………………………

2……………………………….

3……………………………….

4……………………….

5……………………………….


40

Order in homologous series

Learning outcomes: You should be able to :

describe the systematic approach in naming members of homologous series.

describe the order in the physical and chemical properties in homologous series.

Activity 17

a) Name the homologous series for

(i) Butan-1-ol : …………………………………..

(ii) Compound P : ………………………………….

(iii) Compound R : …………………………………

(iv) Compound S : ………………………………..

b) Write the molecular formula of

(i) compound P : …………………………………..

(ii) compound Q : ……………………………………

(iii) compound R : …………………………………..

(iv) compound S : …………………………………….

Butan-1-ol C4H9OH Compound P

Porcelain chips II

III Hydrogen chloride

Compound Q

I Acidified potassium dichromate(VI) solution

Compound R

ethanol

Compound S IV


41

H FATS

Learning outcomes: You should be able to:

State what oils are

State what fats are

State the importance of oils and fats for body processes

State the sources of oils and fats

List the uses of oils and fats

State the differences between oils and fats

Identify structural formulae for fat molecules of certain fatty acids

State what saturated fats are

State what unsaturated fats are

Compare and contrast between saturated and unsaturated fats

Describe the effects of eating food high in fats on health

Describe the industrial extraction of palm oil

Justify the use of palm oil in the food production

Activity 18 (I) Fill in the blank by choosing the correct answer from the table below. ester solid heart

attack hydrogenation harden stroke carbon high blood

pressure margerine

saturated, ester link

lipid trigleycerides Chlorofom liquid glycerol energy fatty acid

a) Fats , oils and waxes are from a large family of organic compound called ………………...

b) They are natural ……………………..

c) They are product of the reaction between …………………. and ……………………

d) Fats are usually found in animal and they are ………………….while oil is fat from plant

and also from animal but they are ………………………… at room condition.

e) Fatty acids are long straight-chain containing between 12 to 18 ……………… atoms per

molecule.

f) A molecule of glycerol may combine with one, two or three fatty acid to form a monoester, diester

or trimester. A Molecule of water is eliminated when a fatty acid joins to the glycerol molecule

and the resulting bond formed is called an …………………(-COO-).

g) Most fats and oils are …………………….

h) As a group, oil and fats tend to dissolve in organic solvents such as ………………….

i) Fats are an important source of ……………………… for our body.

j) ……………… fats may cause cholesterol to deposit on the blood vessels and making them

……………….. . This can lead to ………………………, ……………………….and

……………………………..

k) Unsaturated fats can be converted to saturated fats by a process called ………………….


42

l) …………………… is made by hydrogenating some of the carbon-carbon double bond in

vegetable oil.

(II) Compare fats and oils

Comparison Oils Fats

Source

Melting point o C < 20 / lower > 20 / higher

Physical state at room temperature

Cholesterol content

Examples Peanut oil, soybean oil Butter , lard

Molecular structure

(III) Write the Similarities of fats and oils

In terms of Similarities

Molecular formula

Type of compound

Type of bond .


43

Activity 19 a) Complete the flow chart below to show the Extraction Process of Palm Oil. b) State 5 benefits of palm oil compared to other vegetable oils i) ………………………………………………………………….

ii) ……………………………………………………………………

iii) …………………………………………………………………..

iv) ………………………………………………………………….

v) ………………………………………………………………….

I NATURAL RUBBER

Learning outcomes: You should be able to :

List examples of natural polymers and their monomers,

Draw the structural formula of natural rubber,

State the properties of natural rubber,

State the uses of natural rubber

Describe the coagulation process of latex

Describe the method used to prevent latex from coagulating,

Describe the vulcanization of rubber,

Describe how the presence of sulphur atoms changes the properties of vulcanised rubber,

Compare and contrast the properties of vulcanised and unvulcanised natural rubber.

Oil palm fruit bunches

Stripping

Pressing

The fresh fruit bunches are sterilized ia large pressure vessels at 140o C for 60-90 min. The heat from the steam kills fungus and bacteria

Breaking down the oil-bearing cells. Crush the palm oil fruits

The mixture is filtered to remove solid or coarse fibre and allow to settle in an a large clarification tank. The oil is skimmed off and dried in a vacuum drier.


44

Activity 20 a) Give explanation for every situation below:

i) Latex coagulate slowly when it is exposed to the air.

ii) When 20 cm3 latex is added with 5cm3 methanoic acid, latex coagulate rapidly.

iii) When 5 cm3 ammonia solution is added to latex, latex does not coagulate.

b) Compare the unvulcanized and vulcanised rubber in the table below.

Aspect Unvulcanised rubber Vulcanised rubber

Structure

Oxidation

Resistance of heat

Strength

Elasticity


45

ACTIVITY 21

1 Base on the diagram above, (a) Name the product formed in step I.

………………………………………………………………………………………

(b) (i) State the reagents needed for step II.

…………………………………………………………………………

(ii) Write the chemical equation for the reaction in step II.

…………………………………………………………………………

(c) (i) Name the type of reaction occurring in step III.

………………………………………………………………………….

(ii) A catalyst is needed for the reaction in step III. Name the catalyst.

…………………………………………………………………………

(d) (i) Describe briefly how to carry out the reaction in step IV.

………………………………………………………………………….

(ii) What do you expect to observe when the reaction in step IV is carried out?

……………………………………………………………………………………

(e) Draw the possible structural formulae of C3H7OH formed in step V.

(f) (i) Name the type of reaction occurring in step VI.

………………………………………………………….

(ii) Give one use for ( C3H6)n formed in step VI.

………………………………………………………….

(g) Compare and explain the sootiness of C3H6 and C3H8 when each of these hydrocarbons is burnt in excess air. [Relative atomic mass: H = 1; C = 12) [4]


46

2 Diagram below shows the molecular formulae of 4 carbon compounds.

(a) Write the general formula of the homologous series of compound B.

……..……………………………………………………………………………………… (b) State the functional group of compound A and compound D

Compound A : ………………………………………………………………………….. Compound D : …………………………………………………………………………..

(c) Compound B shows isomerism. Draw the structural formula of all isomers of compound B.

(d) Compound D and compound C react in the presence of the concentrated sulphuric acid.

(i) Name the product formed from the reaction.

……………………………………………………….…………………………… (ii) State one special characteristic of the product formed.

……………………………………………………….……………………………

(e) Compound A burns in excess oxygen to produce carbon dioxide and water.

(i) Write a balanced chemical equation for the reaction. .................................................................................................................

(ii) 11.2 g of compound A burns in excess oxygen, calculate number of carbon

dioxide molecules formed. [Relative atomic mass C = 12, O = 16 and Avogadro number = 6.02 x 1023]

C4H8 C2H5COOH

C4H9OH C4H10

A B C D


47

CHAPTER 3 : OXIDATION AND REDUCTION A. REDOX REACTIONS Learning Outcomes: You should be able to,

state what oxidation is

state what reduction is

explain what redox reaction is

state what oxidising agent is

state what reducing agent is

calculate the oxidation number of an element in a compound.

relate the oxidation number of an element to the name of its compound using the IUPAC nomenclature.

explain with examples oxidation and reduction processes in terms of electron transfer

explain with examples oxidising and reducing agents in redox reactions.

write oxidation and reduction half-equations and ionic equations.

Activity 1 1) The tables below describe the meaning of oxidation and reduction in terms of (a) loss or gain of oxygen (b) loss or gain of hydrogen (c) transfer of electrons (d) changes in oxidation number

Study each table below carefully and fill in the blanks. (a) Loss or gain of oxygen

Loss or gain of oxygen

Oxidation Reduction

The process of gaining oxygen The process of losing oxygen

Example : Mg + PbO MgO + Pb In the above redox reaction,

Mg gains oxygen to form MgO. This process is called. ……….………………………….

PbO loses oxygen to form Pb. This process is called ……….…………………………....

Mg is a reducing agent because it ………………….. … lead(II) oxide to …………………….

PbO is an oxidizing agent because it ………………… magnesium to………………………..

(b)Loss or gain of hydrogen

Loss or gain of hydrogen

Oxidation Reduction

The process of losing hydrogen The process of gaining hydrogen

Example : H2S + Cl2 2HCl + S

In the above redox reaction

H2S loses hydrogen to form S. The process is called …….. ………………………...

Cl2 gains hydrogen to form HCl. This process is called …….. ……………………….

H2S is a reducing agent because it ………………to …………………… ……..………….


48

Cl2 is an oxidizing agent because it ……………………to……………………………..

(c) Transfer of electrons

Transfer of electrons

Oxidation Reduction

The process of losing electrons The process of gaining oxygen

Example : Redox reaction: 2Na + Cl2 2NaCl Half-equations: Na Na+ + e // Cl2 + 2e 2Cl– In the half-equations above,

Na atom loses electron to form Na+. This process is called …………………………

Cl2 molecule gains electrons to form 2Cl–. This process is called …………………..

Na is a reducing agent because it …………………… to ………………………… ……..

Cl2 is an oxidizing agent because it …………………..to ………………………… …….

(d) Changes in oxidation number

Changes in oxidation number

Oxidation Reduction

The increase in oxidation number The decrease in oxidation number

Example : Chemical equation: 2Na + Cl2 2NaCl

Changes in oxidation number Na : 0 +1 // Cl : 0 –1 Given above are the changes in oxidation number of Na and Cl, state which element is oxidized or reduced and which element is the oxidizing or reducing agent.

Na is ............................. to Na+ : Na is the………………………………..… agent

Cl2 is …………………….to Cl– : Cl2 is the …………………………………. agent

2) What are redox reactions?

…………………………………………………………………………………………………………………. …………………………………………………………………………………………………………………..

Activity 2 The diagram below shows the oxidation and reduction process that occurs in a redox reaction.

CuO + C → Cu + CO2

By drawing arrows, show and label the oxidation and reduction processes occurring in the redox reactions below.

Reduction

Oxidation


49

ZnO + Mg MgO + Zn 2HI + Cl2 I2 + 2HCl

Fe2O3 + 3CO 2Fe + 3CO2 2NH3 + 3Br2 N2 + 6HBr

Activity 3 (a) Fill in the blanks with suitable words. (i) The substance that causes oxidation is called the ………………………….………….. agent

(ii) The substance that causes reduction is called the ……………...…………………….. agent.

(b) State the oxidizing and reducing agents in each of the chemical reactions given below. (i) 2Zn + O2 2ZnO.

Oxidising agent: ……………………………... Reducing agent: …….………………………….. (ii) 2Mg + CO2 2MgO + C Oxidising agent: .…………………….……… Reducing agent: ……..…………………………….. Activity 4 Oxidation numbers of elements can be calculated based on the ‘rules in assigning oxidation numbers’ as stated in the chemistry text book on page 107. Two examples are given below. Examples: a) Determine the oxidation number for the underlined elements

(i) H3PO4 (1×3) + P + (-2×4) = 0 3 + P + (-8) = 0

P = 8 – 3 = +5 the oxidation number for phosphorus is +5

(ii) N2H4 2N + (1×4) = 0 2N + 4 = 0

N = – 4/2 = –2 the oxidation number for nitrogen is –2

Answer the following questions. 1. Determine the oxidation number for the underlined elements.

(a) Fe (b) MgCl2

(c) Na2O


50

(d) CO2

(e) SO42– (f) MnO4

–

2. Calculate the oxidation number for chlorine and nitrogen in their compounds below and write its

oxidation in the spaces provided. 3 Write the oxidation number for the underlined element in the boxes provided and state whether the

element undergoes oxidation or reduction process. Part (a) is shown as an example

a) Mg + CuO MgO + Cu Process b) 2Fe + 3Cl2 2FeCl3 Process c) Cr2O7

2– Cr3+

Process

d) 4HCl + MnO2 MnCl2 + Cl2 + 2H2O Process e) Cu + 2AgNO3 Cu(NO3)2 + 2Ag Process

Chlorine compound

HCl HClO HClO2 ClO2 HClO3 HClO4

Nitrogen Compound

NH3 N2O NO NO2– NO2 NO3

–

0 +2

Oxidation


51

Substance undergoes oxidation:

Substance undergoes reduction:

Oxidising Agent: Reducing Agent:

Oxidation half-equation: Reduction half-equation:

4 Determine the oxidation number for the underlined elements in the table below and name the compound using the IUPAC nomenclature.

Formula of compound Oxidation number Name of compound

CuSO4 Cu2O CrCl3

Cr2O72–

NO3–

NO2–

NH4+

MnO2 Activity 5 For each of the chemical reactions below, (a) write the oxidation and reduction half-equations, (b) identify the following: (i) Substance that undergoes oxidation (iii) Oxidising agent (ii) Substance that undergoes reduction (iv) Reducing agent Example: Zn + 2Ag+ Zn2+ + 2Ag Based the ionic equation given, it is known that the oxidation number of Zn increases from 0 to +2. Hence zinc undergoes oxidation to form Zn2+ Answer: Oxidation half-equation: Zn Zn2+ + 2e- Reduction half-equation: 2Ag+ + 2e- 2Ag Substance undergoes oxidation: Zinc (Zn) Substance undergoes reduction: Silver ion (Ag+) Oxidising agent : Silver ion (Ag+) Reducing agent : Zinc (Zn) Based on the chemical equation given, complete the flow charts below. a)

Cl2 + 2I 2Cl + I2


52

Mg + 2HCl MgCl2 + H2

Substance undergoes

oxidation:




Pb + Br2 PbBr2

Substance undergoes

oxidation:




4Na + O2 2Na2O

Substance undergoes

oxidation:




b) c) d)


53

Activity 6(a) Writing ionic equation from given oxidation and reduction half-equations: Example: Given: Oxidation half-equation: Mg Mg2+ + 2e Reduction half-equation: Ag+ + e Ag [In order to write an ionic equation from the two given half-equations, the electrons that were transferred from Mg to the Ag must be equal. Hence two Ag+ will receive two electrons from an atom of Mg.]

Mg Mg2+ + 2e 2Ag+ + 2e 2Ag

Mg + 2Ag+ Mg + 2Ag Answer: Ionic equation: Mg + 2Ag+ Mg + 2Ag Based on the given oxidation and reduction half-equations, write the ionic equation for the reaction (a) Oxidation half-equation: Mg Mg2+ + 2e Reduction half-equation: Cu2+ + 2e Cu Ionic equation: ………………………………………………………………………………… (b) Oxidation half-equation: Al Al3+ + 3e Reduction half-equation: Ag+ + e Ag Ionic equation: ………………………………………………………………………………… (c) Oxidation half-equation: Fe2+ Fe3+ + e Reduction half-equation: Br2 + 2e 2Br–

Ionic equation: ………………………………………………………………………………… (d) Oxidation half-equation: 2I– I2 + 2e Reduction half-equation: Cl2 + 2e 2Cl–

Ionic equation: ………………………………………………………………………………… (e) Oxidation half-equation: Cl2 + 2e 2Cl–

Reduction half-equation: Fe2+ Fe3+ + e Ionic equation: ………………………………………………………………………………… (f) Oxidation half-equation: Fe Fe2+ + 2e Reduction half-equation: O2 + H2O + 4e 4OH–

Ionic equation: …………………………………………………………………………………


54

Activity 6(b) Changing Iron(II) ions, Fe

2+ to Iron(III) ions, Fe

3+

Procedure: 1. 2.0 cm3 of ............................................. solution is added into a test tube.

2. A few drops of ...................... …….............. were added drop by drop into the test tube and mixture

is heated.

3. The ……………………………… is recorded.

4. Observation:

The colour of iron(II) sulphate solution changed from ....................... to ................... The bromine water changed from ....................... to ........................ . In order to detect presence of iron(III) ion in the solution, add .......................... ........................................ ………............... in excess. ..................................(colour) precipitate of iron(III) hydroxide is formed.

5. Concept: a) Iron(II) ion is ……………… to iron(II) ion by ……………………………. At the same time

…………… …………………………… is reduced to ……………………………. Ion.

b) Oxidation and reduction half-equations:

Fe2+ ............. + .............. (Oxidation) Br2 + ............ .................. (Reduction)

c) Ionic equation: ………………………………………………………………………………………..

d) Iron(II) ions .................. electrons to become iron(III) ions. Iron(II) ions are ...................................

e) Bromine molecules ............. electrons to form bromide ions. Bromine molecules are ………….....

f) Reducing agent: ................................... Oxidising agent: ...................................

(1) 2.0 cm3 of Iron(II)

sulphate solution (light green)


55

Changing Iron(III) ions, Fe3+ to Iron(II) ions, Fe2+

Procedure: 1. Add 2.0 cm3 of ............................................. solution into a test tube.

2. Add ......................................... into the same test tube and heat the mixture.

3. Record the .............................................................

4. Observation:

a. The colour of iron(III) chloride solution changed from ............................ to ..............................

b. In order to detect the presence of iron(II) ion in the solution, add ................. ...................... in

excess. A ................ ........................... (colour) precipitate of iron(II) hydroxide is formed.

5. Concept: a). Iron(III) ion is ....................... to iron(II) ion by ................. ….................. At the same time, zinc is

......................... to .............................. ion.

b) Reduction and oxidation half-equations:

Fe3+ + .......... .............. (Reduction) Zn ............... + ................ (Oxidation) c) Ionic equation: ……………………………………………………………………………………

d) Iron(III) ions …............. electrons to become iron(II) ions. Iron(III) ions are ….......................

e) Zinc atom …................. electrons to form …................ ions. Zinc atoms are ….......................

f) Reducing agent: ...................................... Oxidising agent: ........................................

Activity 7 Displacement of metal from its salt solution

M(s) + AB(aq) MB(aq) + A(s) Oxidation half-equation: M Mn+ + ne

The following statements describe the displacement of metal from its salt solution by another element. Fill in the blanks with the correct word(s).

(1) 2.0 cm3 of

iron(III) chloride solution (yellow)


56

1. A ..…………. (more/ less) electropositive element is oxidized more …………………. (easily / harder )

and acts as a ……………………….. (stronger / weaker) reducing agent.

2. An element that is located higher in the electrochemical series can displace other elements that are

positioned (i)……………………….. in the electrochemical series from its salt solution.

Example: Displacement copper from copper(II) sulphate solution. Ionic equation: Zn + CuSO4 ZnSO4 + Cu Half-equation: Zn Zn2+ + 2e [ Oxidation ] Half-equation: Cu2+ + 2e Cu [ Reduction ] Zinc, Zn is (ii) ……………. electropositive than copper, Cu. Thus Zn atom releases (iii) ……………. electron to form ion Zn2+. The electrons are transferred from (iv)…………… ……….….. to (v)…………………………….. The copper(II) ion, Cu2+ receives the two electrons from zinc to form copper atom, Cu. Zn atom acts as a (vi) …………………… …………… and Cu2+ ion acts as a (vii) ………………………………… …………………

Activity 8 (a) Halogen in aqueous and 1,1,1-trichloroethane Complete the table below by stating the colur of halogen in aqueous solution and in 1,1,1-trichloroethane

Halogen Colour of halogen

In aqueous solution In 1,1,1,-trichloroethane

Chlorine

Bromine

Iodine

Displacement of halogens from their halide solutions by other halogens.

Fill in the blanks by choosing the most appropriate word from the list displayed above. 1) Halogens are located in Group ………….. of the Periodic Table


57

2) Halogen elements tend to ………………… electrons to achieve a stable octet electron arrangement. 3) Halogens are reduced to …………… ions 4) The electronegativity of halogens or their tendency to accept electrons ………………….. when going

down Group 17. 5) Thus, the strength of halogens acting as ………………… ….……….. decreases when going down

the group 17. 6) In displacement reaction of halogen, a ……….. electronegative halogen will displaces a …………… electronegative halogen from its halide solution. Activity 9 Transfer of electrons at a distance A. The diagram shows the set up of apparatus for the redox reaction involving bromine water and

potassium iodide solution.

The following statement describe the redox reaction between bromine and potassium iodide solution. Fill the blanks with the appropriate word(s). 1. Electrons flow from …………….. to ….…………through the wire. 2. The colour of potassium iodide solution changes from ………………………to ………………………. 3. The colour of bromine water changes from ………………… to ………………… …………………….... 4. Oxidation half-equation: …………………………………………………………………………………..

Reduction half-equation: …………………………………………………………………………………..

5. Overall Ionic Equation : …………………………………………………………………………………….. 6. Oxidising agent: ……………………………… 7. Reducing agent: ………………………… 7. To confirm that the brown solution formed is iodine solution, a chemical test can be carry out.


58

Method 1

Some ....................... ......................... is added into a test tube containing the brown solution. A dark blue colouration is obtained if iodine is present. Method 2 2 cm3 of ........................................... is added into a test tube containing the brown soltion. The

test tube is then stopperred and its mixture .................. If the lower layer [1,1,1-trichloroethane

layer] is ............................. in colour, then it is confirmed iodine is present.

B The diagram below shows the set up of apparatus of redox reaction between acidified potassium

manganate(VII) and potassium iodide soultion.

Below are some of the facts about the redox reaction between acidified potassium manganate(VII)

and potassium iodide soultion. Answer the following question The half-equation for the reaction that occurs around the carbon rod on the left is as follow

MnO4- + 8H + + 5e Mn 2+ + 4H2O

a) State the change in oxidation number of manganese.

…………………………………………………………………………..

b) A brown solution was observed forming around the carbon rod on the right. Name the brown

solution formed. ..……………………………………………………………………………….. c) Write a half-equation for the formation of the brown solution.

………………………..…………………………………………………………………………..

d) Write the ionic equation for the reaction between acidified potassium manganate(VII) and iodide ion.

…………………………………………………………………………………………………………….

Carbon rod

Acidified Potassium Manganate (VII) solution, 1.0 mol dm-3

Potassium Iodide Solution, 1.0 mol dm-3

Dilute Sulphuric acid, 1.0 mol dm-3


59

e) On the diagram above, show the direction of the flow of electron by using arrows.

B. RUSTING AS A REDOX REACTION

Learning Outcomes : You should be able to,

state the conditions for the rusting of iron

state what corrosion of metal is.

describe the process of rusting in terms of oxidation and reduction. generate ideas on the use of other metals to control rusting,

explain with examples on the use of a more electropositive metal to control metal corrosion,

Activity 10 Rusting as a redox reaction

1. Fill in the blanks with suitable word. a) Oxidation of metal is called (i) ………………………….. while (ii) the oxidation of iron is called

……………………

Oxidation half-equation for corrosion of metal: M Mn+ + ………….

b) The presence of (i)……………………. and (ii)……………………………. will cause iron to rust,

The rusting can be accelerated by adding (iii)………………………. or (iv) ……………………….

c) Copper forms a green coating as a result of corrosion, it contains ……………….. ions.

d) Metals like (i)………………………. and (ii)……………………… forms a very tough oxide layer

which adhere tightly to the surface of the metal and thus preventing further oxidation. This protect

the metals from further corrosion.

e) To prevent corrosion, metal A can be coated with a layer of metal B which is more

(i)………………………. than A. Metal B will corrode first, thus preventing metal A from corrosion.

In this situation, metal B is also called the (ii)……………………. metal.

f) If iron is in contact with another (i)…………………………which is less electropositive than iron,

the rate of rusting for iron will be (ii)………………………………….

g) Zinc is used to protect iron or steel by coating a thin layer of zinc onto it, this process is called

(i)……………………………….. In industry, zinc is chosen to serve the purpose rather than other

metals because zinc is (ii)…………………………………… in cost.

h) Some household and bathroom equipments are coated with a layer of shiny finishes, the metals

usually used for these coatings are (i)…………………………. and

(ii)………………………………………. .


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2. Mechanism of rusting of iron in the present of water and oxygen involves some chemical

reactions. Figure below shows an unlabeled diagram of a water droplet on the surface of iron.

Write the chemical equations or half equations for the processes below.

a) The formation of iron(II) ions from the metal: When iron contacts with water, the iron surface oxidizes to form iron(II) ions. Oxidation half-equation: ……………………………………………………………………….

b) The formation of hydroxide ions:

Electrons released by iron then flow to the edges of the water droplets, where there is a high concentration of dissolved oxygen. At the cathode area, water and oxygen molecules receive electrons and are reduced to form hydroxide ions. Reduction half-equation: ……………………………………………………………………………..

c) Formation of green precipitate. Fe2+ readily combines with OH- to form insoluble solid Fe(OH)2 Chemical equation: …………………………………………………………………………………..

d) Using chemical equations in (a), (b) and (c), the reaction between iron, water and oxygen to form iron(II) hydroxide can be summarized into a overall chemical equation. Chemicall equation: ……………………………………………………………………………………..

e) With excess oxygen, the rust is formed: The Fe2+ ions are further oxidized to form Fe3+ ions, which reacts with OH- ions to form the hydrated iron (III) oxide, Fe2O3. xH2O, known as ‘rust’.

Chemical equation: ……………………………………………………………………….

f) Complete the diagram above by filling the blanks in the spaces provided.


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Activity 11 Answer the questions below. 1. Name three main ways to prevent rusting.

(i) …………………………………………………………………………………………………………….

(ii) …………………………………………………………………………………………………………….

(iii) ……………………………………………………………………………………………………………

2. Galvanising involves coating an iron or steel sheet with a thin layer of………………………………

3. Name three metals that can be used in sacrificial protection for an underground pipe.

(i) …………………………..….(ii) ……………..………………. (iii) …………………………………

4. Name a reagent that is usually used to detect the presence of iron(II) ion in an experiment to

investigate the rusting of iron.

………………………………………………………………………………………………..

Activity 12 1 Diagram below shows the apparatus set-up for the experiment to study the effect of metals P

and Q on the rusting of iron nail. The results are recorded after one day.

Test tube

Metal Experiment After 1 day Observation

A Iron only

Some dark blue precipitate.

B Iron with metal P

Large amount of dark blue precipitate

C Iron with metal Q

No dark blue precipitate. Solution turns pink.

(a) Write the half-equation for the formation of iron(II) ion from iron.

.................................................................................................................................................

(b) State the function of potassium hexacyanoferrate(III) solution in the experiment and describe its change in colour if a positive result occurred.


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................................................................................................................................................... ……………………………………………………………………………………………………………

(c) Which test tube shows the highest rate of rusting of iron? Explain your answer. ..................................................................................................................................................... ......................................................................................................................................................

(d) Arrange the metals Fe, P and Q in decreasing order of electrochemical series.

..............................................................................................................................

(e) (i) What happens to metal Q in test tube C?

….....................................................................................................................................

(ii) Suggest a metal that can be used as metal Q.

…....................................................................................................................................

(f) State the ion that causes the solution in test tube C to turn pink. ...................................................................................................................................................

C. THE REACTIVITY SERIES OF METALS WITH OXYGEN AND ITS APPLICATION Learning Outcomes : You should be able to,

compare the differences in the vigour of the reactions of some metals with oxygen.

deduce the reactivity series of metals.

determine the position of carbon and hydrogen in the reactivity series of metals.

state what the reactivity series of metals are.

describe the extraction of iron and tin from their ores.

explain the use of carbon as the main reducing agent in metal extraction.

use the reactivity series of metals to predict possible reactions involving metals

Activity 13 1. Figure below shows the set-up of apparatus for an experiment to determine the order of

metals in the reactivity series. Solid potassium manganate (VII) is heated to release oxygen gas to react with hot metal powder.

The experiment is carried out using metal powders of copper, zinc, magnesium and lead . The observation of the experiments on the metal powders of copper, zinc, magnesium and lead in the experiments are shown in table below.


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Type of metal Observation

Copper Faint glow

Zinc A bright flame spreads slowly

Magnesium A bright white shiny flame spreads quickly

Lead Red hot and embers slowly

(a) Based on the observations in table above, arrange copper, zinc, magnesium and lead

in descending order of reactivity of metal towards oxygen.

Descending order of reactivity of metals with oxygen.

(b) Name two other substances that can be used to produce oxygen gas in the experiment (i) ……………………………………………… (ii) ………………………………………………

(c) Write a balance chemical equation for each of the reaction below. (i) Copper + oxygen ………………………………………………………………………………………….. (ii) Zinc + oxygen

……………………………………………………………………………………………

(iii) Magnesium + oxygen ……………………………………………………………………………………………

(iv) Lead + oxygen ……………………………………………………………………………………………

2) According to the chemical equation below, carbon reacts with oxygen to produce ……………

………………………….. gas.

C ( s ) + O2 (s ) → CO2 ( g )

3) Based on the reactivity series of metals with oxygen, carbon able to displace a …………… ……………….. metal from its metal oxide. Thus, by heating a mixture of metal

oxide and carbon , the reactivity of carbon can be determined.

0 Oxidation +4

C ( s ) + 2PbO (s ) → CO2 ( g ) + 2Pb(s) +2 Reduction 0


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4) Carbon is ………………… to carbon dioxide and lead (II) oxide is reduced to lead. 5) Carbon acts as a (i)…………………………….. agent which displaces a metal from its oxide while the metal oxide is the (ii) …………………….agent.

6) Carbon is not able to displace a …………… ………………. metal from its metal oxide. Hence,

there is no displacement reaction when a mixture of magnesium oxide and carbon is heated.

7) Carbon is positioned in between (i) …………………………and (ii) …………….. in the reactivity

series.

8) Oxides of metals W,X, Y, Z are heated with equal amount of carbon powder in an experiment to compare their reactivity with carbon. The changes observed are recorded in the table below.

Mixture Observation

Carbon + oxide of W No change

Carbon + oxide of X Dim glow. Grey residue is formed

Carbon + oxide of Y No change

Carbon + oxide of Z Bright glow. Brown residue is formed

(a) Based on the observation , classify the metals in groups that are

(i) more reactive than carbon: ………………………………………………………………… (ii) less reactive than carbon: …………………………………………………………………

(b) Suggest a possible element for metals X and Z

X : …………………………………… Z : ………………………………………….

(c) The reactivity of W and Y can be compared by heating an equal amount of W powder with oxide of Y in a crucible using the same apparatus set-up.

(i) What is the expected observation if W is more reactive than Y? Explain your answer ……………………… ……………………………………………………………………… ………………………………………………………………………………………………… (ii) Suggest the possible elements for W and Y W : ………………………………… Y : ……………………………………………….. (iii) Write a balanced chemical equation for the reaction between W (charge of +2) and

oxide of Y (charge of +3). …………………….. …………………………………………………………………..


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(iv) Identify the reducing agent and oxidising agent in the reaction between W and oxide

of Y. Reducing agent: ………………..……… Oxidising agent: ……………………………

9. Complete the reactivity series of metals with oxygen given below by writing the name of the missing elements in the spaces provided. Reactivity decreases

Potassium

Calcium

Aluminium

Iron

Tin

Mercury

Gold

10. The following shows part of the increasing order of reactivity series of metals with oxygen.

K Na Ca Mg Al Zn Fe Sn Pb Cu Hg Ag Au Insert the positions of carbon and hydrogen in the above series by using arrows to indicate its

position. 11. Predict what will be observed when, (a) hydrogen gas is heated with copper (II) oxide in tube. ……………………..…………………………………………………………………………............ …………………….…………………………………………………………………………………. (b) a piece of burning magnesium ribbon is dropped into a gas jar filled with carbon dioxide.

……..……………………………………………………………………..……………………………

…………………………………..…………………………………………………………………….

(c) carbon is heated with magnesium oxide. …………………………………………………………………………………………....................


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12. Complete the following table by giving the main mineral in ore and the metal extracted from its ore.

Ore Main mineral in ore

Metal extracted Name Formula

(a) Bauxite

(b) Hematite

(c) Magnetite

(d) Cassiterite

D. ELECTROLYTIC AND CHEMICAL CELLS Learning Outcomes : You should be able to,

explain with examples the oxidation and reduction reactions at the electrodes of various chemical cells.

explain with examples the oxidation and reduction reactions at the electrodes of various electrolytic cells.

state the differences between electrolytic and chemical cells in terms of basic structure, energy conversion and the transfer of electrons at the electrodes .

compare and contrast electrolytic and chemical cells with reference to the oxidation and reduction process.

Activity 14 1) Below are listed the differences between electrolytic and chemical cells. Complete the statements by filling in the blanks with the correct words.

It requires a source of ……………………………………. The electrodes may be of the ………… material such as …………………

It does not require a source of ……………………………………

The electrodes must be of two …………………...... metals.


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2) The figure above shows the electrolysis process of molten lead (II) bromide. Answer the questions

below. (a) State the ions contain in the molten lead (II) bromide. ………………………………………….

(b) Pb2+ ions move to the (i) ……………………. while Br ions move to the (ii) ……………………

(c) Br ions act as the (i) ……………………. agent, losing electrons at the electrode to become

(ii) …………………… molecules. Thus, Br ions undergo (iii) ……………………….. .

(d) Oxidation half-equation: …………………………………………………….

(e) Pb2+ ions act as the (i) ……………………. … agent, accepting electrons to become

(ii) ……………………….. metal. Thus, Pb2+ ions undergo (iii) ……..……….. .

(f) Reduction half-equation : …………………………………………………...

The electrical energy causes …………………… reactions to occur at electrodes.

Electrons flow from the ……………. electrode (anode) to the ……………. electrode (cathode) through the …………………. (external circuit)

The chemical reactions that occur at the electrodes produce an ………………………………………

Electrons flow from the more ………………. metal …………… terminal) to the less ………………… metal (……………………. terminal)


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3) Figure below shows a chemical (voltaic) cell.

a) Label the negative terminal and positive terminal and show the direction of the flow of electrons

by using arrows the above figure.

b) Write the half-equation for the reaction at the positive terminal.

…………………………………………………………………………………………………...

c) Write the half-equation for the reaction at the negative terminal.

…………………………………………………………………………………...............

d) State the substance that undergoes oxidation.

…………………………………………………………………………………………………...

e) State the substance that undergoes reduction.

…………………………………………………………………………………………………...

4) Similarities and differences of the redox reactions in electrolytic cell and a voltaic (chemical) cell

Similarities

In both cells,

electrons are transferred from the …………… agent to the ……………… agent.

oxidation occurs at the anode.

…………………… occurs at the cathode

Differences

Electrolytic cell Chemical cell


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70

CHAPTER 4 : THERMOCHEMISTRY A ENERGY CHANGES IN CHEMICAL REACTION

Activity 1:

(a) What is an exothermic reaction?

An exothermic reaction is a chemical reaction that gives out heat to the surroundings.

Heat energy given out from the reaction is (1)…………………………to the surroundings

The temperature of the surroundings (2)……………………….

(b) What is an endothermic reaction?

An endothermic reaction is a chemical reaction that absorbs heat from the surroundings .

The reactants (3) …………………. heat energy from the surroundings. The temperature of the

surroundings (4) ……………………….

Activity 2

(a)

Identify the following reactions as exothermic or endothermic reaction by writing a ‘’ at the appropriate box as shown in Question (a).

Reaction Exothermic Endothermic

(a) Combustion of ethanol √

(b) Burning of magnesium

(c) Neutralisation between acid and alkali

(d) Adding water to concentrated sulphuric acid

Learning Outcomes :


State what exothermic reaction is,

State what endothermic reaction is,

Identify exothermic reactions,

Identify endothermic reactions,

Give examples of exothermic reactions,

Give examples of endothermic reactions,

Construct energy level diagrams for exothermic reactions,

Construct energy level diagrams for endothermic reactions,

Interpret energy level diagram,

Interrelate energy change with formation and breaking of bonds,

Describe the application of knowledge of exothermic and endothermic reactions in everyday life.


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(e) Photosynthesis

(f) Reaction between acid and magnesium

(g) Reaction between acid and calcium carbonate

(h) Dissolving ammonium salt in water

(i) Thermal decomposition of copper(ll) carbonate

(j) Thermal decomposition of zinc nitrate

(b) The amount of heat energy released or absorbed during a chemical reaction is called the heat of

reaction.

It is given a symbol (1)………………. and the unit is (2) …………………..

(c)

(d)

The heat of reaction , Δ H = H products - H reactants

(a) Exothermic reaction : The reactants lose heat energy to form the products . Thus the products

formed have less energy than the reactants, Therefore, Δ H is (3)…………………

(b) Endothermic reaction : The reactants absorb heat energy to form the products . Thus the

products formed have (4) ……………energy than the reactant. Therefore, Δ H is (5)…………….

List two other examples of exothermic and endothermic reaction

Exothermic reaction Endothermic reaction

1)

2)

Activity 3 :

(a) Energy level diagram


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(i)

(ii)

(iii)

Energy level diagram for exothermic reaction :

The products have less energy than the reactants,

Energy

ΔH = negative

Construct the energy level diagram based on the given chemical equation,

Mg(s) + H2SO4 (aq) MgSO4 (aq) + H2 (g) ΔH = -467 kJ

(reactants) ( products )

Energy level diagram for endothermic reaction :

The products have more energy than the reactants,

Energy

ΔH = positive

Construct energy level diagram based on the given chemical equation

CaCO3(s) CaO(s) + CO2 (g) ΔH = + 178 kJ

Information that can be obtained from the energy level diagram ,

reactants

products

reactants

products


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Energy

ΔH = - 190 kJ

Figure 1

Figure 1 shows the energy level diagram for the reaction between zinc and copper(ll)

sulphate,

The reaction between (1) ……………and (2)…………………. is an (3)

…………………….. reaction.

During the reaction, the temperature of the mixture (4) ………………………

The total energy of one mole of (5)……………. and one mole of (6) …………… is

(7)…………. than the total energy of one mole of copper and one mole of zinc

sulphate by (8)……………………. kJ

When one mole of (9)………………….. reacts with one mole of (10)…………to form

(11)…………….. .. mole of copper and (12)……………….. mole of zinc sulphate,

(13)…………………….. kJ of heat is (14) …………………………

Energy

ΔH = +53 kJ

Figure 2

Figure 2 shows the energy level diagram for the reaction between hydrogen gas and iodine

The reaction between (15)……………and (16)…………………. is an

(17)……………… reaction.

During the reaction, the temperature of the mixture (18)……………………

The total energy of one mole of (19)……………. and one mole of (20)…………….

is (21) ………than the total energy of two moles of hydrogen iodide by (22) ……kJ

When one mole of (23)………………….reacts with one mole of (24) ………………

to form (25) …………….mole of hydrogen iodide (26)………..kJ of heat is

(27)…………………

Zn + CuSO4

Cu + ZnSO4

H2 (g) + I2(g)

2HI (g)


74

(b) (i) A chemical reaction involves (1) ....……… (2) ............... of the reactants and

(3)…………….. (4) ........................of the product

(ii) Bonds breaking always(1) …………. energy and bonds formation always

(2) ………………… energy

Bond breaking Bond formation

(iii) If the energy absorbed during bonds breaking is less than the energy released during

bonds formation ,energy is (1)………………….. to the surrounding.

The reaction is an (2) ……………….. reaction

(iv) If the energy absorbed during bonds breaking is more than the energy released

during bonds formation, energy is(1)…………………………. from the surrounding.

Hence it is an (2) ……………………reaction

(c) Explain the application of exothermic and endothermic reaction in our daily lives.

(i)

(ii)

Instant cold packs :

Instant cold packs are used to treat (1)…………………………………………………, have

separate compartments of (2) …………………and (3)……………………in a plastic bag. When

the barrier between the two is broken by squeezing the outer bag, the

(4)…………..…………………… dissolves in the(5) ……………….endothermically to provide

instant coldness.

A reusable heat pack:

……………………………………………………………………………………………………

……………………………………………………………………………………………………

……………………………………………………………………………………………………


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B HEAT OF PRECIPITATION

HEAT OF REACTION Activity 4: Match the chemical equation with the type of reaction below :

Chemical equation

Type of reaction

HNO3 + KOH KNO3 + H2O Precipitation

C2H5OH + 3O2 2CO2 + 3H2O Displacement

Mg + CuSO4 MgSO4 + Cu Neutralization

Pb(NO3)2 + 2KI PbI2 + 2KNO3 Combustion

HEAT OF REACTION The change in the amount of heat in a chemical reaction

Symbol : ΔH The

HEAT OF PRECIPITATION

HEAT OF DISPLACEMENT

HEAT OF NEUTRALIZATION

HEAT OF COMBUSTION

The heat change in a reaction can be calculated using the formula , H = mcӨ m = mass of solution, g c = specific heat capacity of the solution, J g-1 oC-1 Ө = temperature change , 0C Assumption : i) The solution is dilute, it has the same density as water , 1 g cm-3 ( 1 cm3 = 1 g ) ii) The solution has the same specific heat capacity as water, 4.2 J g-1 oC-1

Learning Outcomes You should be able to:

State what heat of reaction is,

State what heat of precipitation is,

Determine the heat of precipitation for a reaction,

Construct an energy level diagram for a precipitation reaction,

Solve numerical problems related to heat of precipitation


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Activity 5 : (a) What is meant by heat of precipitation ? ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………….. (b) To determine the heat of precipitation of silver chloride, AgCl Procedure : 1. Measure 25 cm3 0.5 mol dm-3 silver nitrate solution and pour it into the polystyrene cup,

Example :

Calculate the amount of heat change when the temperature of 200 cm3 of water is raised from 280C to 400C, Q = mcӨ m = 200 g = 200 g x 4.2 J g-1 oC-1 x 12 0C c = 4.2 J g-1 oC-1 = 10080 J Ө = 40 - 28 = 12 0C = 10.08 kJ

Guidelines for the calculation of the heat of reaction Steps to follow: Step 1 - Calculate the heat change using the formula, H = mcӨ ( p Joule ) Step 2 - Write chemical equation or ionic equation for the reaction that occurs Step 3 - Calculate the number of moles of reactant that reacts using either the following formulae : Number of moles = mass = q mol or molar mass Number of moles = MV ( q mol) M : Molarity of the solution (Solution) V : volume of the solution in dm3 Step 4 - Link the number of moles of reactants ( step 3 ) with the heat change ( step 1 ) q mol of reactants react heat lost/gain is p J

∴ 1 mol of reactants react heat lost/gain is p J

q Heat of reaction , ΔH = +/- p kJ mol-1

1000 x q = +/- r kJ mol-1 Note : “ + “ is used for endothermic reaction and “-“ is used for exothermic reaction

Step 5 - Draw the energy level diagram

25 cm3 0.5 mol dm

-3

sodium chloride solution

25 cm3 0.5 mol dm

-3

silver nitrate solution


77

2. Put the thermometer into the silver nitrate solution. Record the initial temperature, 3. Measure 25 cm3 0.5 mol dm-3 sodium chloride solution and record the initial temperature, 4. Pour the sodium chloride solution quickly into the silver nitrate solution in the polystyrene cup. 5. Stir the solution mixture with the thermometer and record the highest temperature achieved. Result : Initial temperature of silver nitrate solution = 28.5 0C Initial temperature of sodium chloride solution = 29.5 0C Highest temperature of the mixture = 32.0 0C Calculation

Step 1 : Calculate the heat change using the formula H = mcӨ

Temperature change, Ө = 32.0 0C - 29.0 0C = 3.0 0C Heat change , H = mcӨ m = ( 25 + 25 ) g = 50 g c = 4.2 J g-1 oC-1

Ө = 3.0 0C H =(1) ……….........J

Step 2: Write balanced chemical equation or ionic equation for the reaction that occurs

Chemical equation : AgNO3 (aq) + NaCl(aq) AgCl (s) + NaNO3 (aq) Precipitate

Ionic equation : (2)………………………………………………………. Deduce the mole ratio from the ionic equation : (3)…………mol silver ion, Ag+ react with (4) ……… mol of chloride ion, Cl- to produce (5)……………. mol of silver chloride , AgCl.

Step 3 : Calculate the number of moles of reactant that reacts, Use the formula : n = MV ( V in dm

3 )

Number of moles of silver ion = the number of moles of silver nitrate = (6) …………………….. mol Number of moles of chloride ion = the number of moles of sodium chloride = (7)…………………….. mol Number of moles of silver chloride formed = (8) ………………….. mol

Average initial temperature = 29.00C


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Step 4 Calculate the heat of precipitation of silver chloride, ΔH Step 5 Energy level diagram

When (9) ….. mol of silver chloride formed, heat released is (10) .…….. When 1 mol of silver chloride formed, heat released is (11)...................... Heat of precipitation of silver chloride, ΔH = (12) - ……………kJ mol – 1 Draw the energy level diagram for the reaction that occurs in this experiment (13)

(c) (d)

Calculate the heat change when 200 cm3 of 0.5 mol dm-3 calcium chloride, CaCl2 solution is added to 200 cm3 of 0.5 mol dm-3 sodium carbonate, Na2CO3 solution if the heat of precipitation of calcium carbonate, CaCO3 is +12.6 kJ mol-1 [ Specific heat capacity of solution : 4.2 J g-1 0C-1 . Density of solution : 1 g cm-3 ] The thermochemical equation for the precipitation of silver chloride is as follows : Ag+ (aq) + Cl- (aq) AgCl ΔH = –65.5 kJ mol-1

Calculate the temperature change when 100 cm3 of 0.5 mol dm-3 silver nitrate, AgNO3 ,

solution is added to 100 cm3 of 0.5 mol dm-3 potassium chloride, KCl solution


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C HEAT OF DISPLACEMENT Activity 6 (a) What is meant by the heat of displacement ? ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………….. (b) To determine the heat of displacement of copper from a copper (ll) sulphate solution by zinc.

Procedure : 1. Measure 25 cm3 0.2 mol dm-3 copper(ll) sulphate solution and pour into a polystyrene cup. 2. Put the thermometer into the copper(ll) sulphate solution. Record the initial temperature, 3. Add half a spatula of zinc powder (in excess) quickly into copper(ll) sulphate solution. 5. Stir the mixture with the thermometer and record the highest temperature achieved. Result : Initial temperature of copper(II) sulphate solution = 30.0 0C Highest temperature of the mixture = 40.0 0C Calculation


Changes of temperature, Ө = 40.0 0C - 30.0 0C = 10.0 0C Heat change , H = mcӨ m = 25 g c = 4.2 J g-1 oC-1

Ө = 10.0 0C H = (1)…………………………….. J

Step 2: Write balanced chemical equation or ionic equation for the reaction that occurs

Chemical equation : Zn (s) + CuSO4(aq) Cu (s) + ZnSO4 (aq) copper displaced

Deduce the mole ratio from the equation : (2)……… mol copper metal, Cu is displaced from (3) …………….. mol of copper(ll) sulphate solution, CuSO4 by zinc

Step 3 : Calculate the number of moles of reactant that

Number of moles copper(ll) sulphate = (4)…………………….. mol Number of moles of copper = (5)…………………….. mol

zinc powder

25 cm3 0.2 mol dm

-3

copper(ll) sulphate solution

Learning Outcomes, You should be able to:

State what heat of displacement is,

Determine the heat of displacement,

Construct an energy level diagram for a displacement reaction,

Solve numerical problems related to heat of displacement,


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reacts

Step 4 Calculate the heat of displacement of copper, ΔH Step 5 Energy level diagram

When (6) ….. mol of copper is displaced, the heat released is (7) .……..

∴ When 1 mol of copper is displaced, the heat released is (8).................

Heat of reaction , ΔH = (9) ……………… kJ mol – 1

Draw the energy level diagram for the reaction that occurs in this experiment (10)

(c) Figure shows an experiment carried out to determine the heat of displacement of silver from silver nitrate by copper metal. Based on figure above, calculate the heat of displacement for the reaction. (d)

In an experiment, excess magnesium powder is added to 50 cm3 of 0.25 mol dm-3

iron(ll) sulphate solution at 29.0 0C. The thermochemical equation is shown below,

Mg(s) + Fe2+ (aq) Mg2+ (aq) + Fe (s) ΔH = -80.6 kJ mol - 1 What is the highest temperature reached in this experiment ?


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D HEAT OF NEUTRALIZATION

Activity 7 (a) What is meant by the heat of neutralization ………………………………………………………………………………………………………….. …………………………………………………………………………………………………………… (b) To determine the heat of neutralisation between a strong acid ( hydrochloric acid ) and a strong alkali ( sodium hydroxide ) Procedure : 1. Measure 50 cm3 2.0 mol dm-3 sodium hydroxide solution and pour it into the polystyrene cup,

2. Put the thermometer into the sodium hydroxide solution. Record the initial temperature, 3. Measure 50 cm3 2.0 mol dm-3 hydrochloric acid solution and record the initial temperature, 4. Pour the hydrochloric acid solution quickly into the sodium hydroxide solution in the polystyrene cup. 5. Stir the mixture with the thermometer and record the highest temperature achieved. Result : Initial temperature of sodium hydroxide solution = 29.0 0C Initial temperature of hydrochloric acid solution = 29.0 0C Highest temperature of the mixture = 42.0 0C Calculation


Changes of temperature, Ө = 42.0 0C - 29.0 0C = (1) ……………….0C Heat change , H = mcӨ m = ( 50 + 50 ) g = 100 g c = 4.2 J g-1 oC-1

Ө = (2) ……………….0C H = (3)…………………………….. J

Step 2: Write balanced chemical equation

Chemical equation (4) ………………………………………………………….

Ionic equation (5) ……………………………………………………….

Learning Outcomes : You should be able to: State what heat of neutralization is, Determine the heat of neutralization, Construct energy level diagrams for various types of neutralization reactions, Compare the heat of neutralization for the reactions between a strong acid and a strong alkali with the heat of neutralization for a reaction between a weak acid and a weak alkali, Explain the difference of the heat of neutralization for a strong acid and a strong alkali with heat of neutralization for a reaction involving a weak acid and/or a weak alkali. solve numerical problems related to heat of neutralization,

50 cm3 2.0 mol dm

-3

sodium hydroxide solution

50 cm3 2.0 mol dm

-3

hydrochloric acid solution

Average initial temperature = 29.0 0C


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or ionic equation for the reaction that occurs

Deduce the mole ratio from the ionic equation : (6)……mol hydrogen ion, H+ react with (7)……mol of hydroxide ion, OH- to produce (8)……………. mol of water , H2O

Step 3 : Calculate the number of moles of reactant that reacts, Use , n = MV

( V in dm3 )

Number of moles of H+ = the number of moles of hydrochloric acid = (9)…………………….. mol Number of moles of OH- = the number of moles of sodium hydroxide = (10)…………………….. mol Number of moles of water formed = (11) ………………….. mol

Step 4 Calculate the heat of neutralisation of hydrochloric acid and sodium hydroxide, ΔH Step 5 : Energy level diagram

When (12) ….. mol of water formed, heat released is (13) .……..

∴ When 1 mol of water formed, heat released is (14) .................

Heat of neutralisation , ΔH = (15) ……………… kJ mol - 1 Draw the energy level diagram for the reaction that occurs in this experiment (16)

(c)

The thermochemical equation for the reaction between ethanoic acid and sodium hydroxide is given below, CH3COOH (aq) + NaOH (aq) NaCH3COO (aq) + H2O (l) ΔH = -55 kJ mol - 1 Calculate the heat given out when 200 cm3 of ethanoic acid 0.5 mol dm-3 is added to 200 cm3 of sodium hydroxide 0.5 mol dm-3


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(d) The energy level diagram of a neutralization reaction is shown in figure below Energy

H2SO4 + 2NaOH

ΔH = - 114 kJ Na2SO4 + 2H2O

When 100 cm3 of 1.0 mol dm-3 sulphuric acid is added to 100 cm3 of 1.0 mol dm-3 sodium hydroxide solution. What is the change in temperature?

E : HEAT OF COMBUSTION Activity 8 : (a) What is meant by the heat of combustion ………………………………………………………………………………………………………. (b) To determine the heat of combustion of ethanol

Learning Outcomes You should be able to :

state what heat of combustion is,

determine heat of combustion for a reaction,

construct an energy level diagram for a combustion reaction,

compare the heats of combustion of various alcohols,

state what fuel value is,

describe the difference between heats of combustion of various alcohols,

describe the applications of fuel value,

compare and contrast fuel values for various fuels,

solve numerical problems related to heat of combustion.


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Experiment to determine the heat of combustion. Procedure : 1. Measure 200 cm3 of water and pour it into a copper can. Record the initial temperature of the water and place the copper can on a tripod stand. 2. Fill a lamp with ethanol and weigh it. Record the mass of the lamp together with its content. 3. Light up the wick of the lamp immediately. Stir the water continuously until the temperature of the water increases by about 30 0C. 5. Put off the flame and record the highest temperature reached by the water 6. Weigh again the lamp and record the mass of the lamp. Result : Mass of lamp and ethanol before burning = 190.55 g Mass of lamp and ethanol after burning = 189.80 g Initial temperature of water = 29.00C Highest temperature of water = 59.00C Calculation

Step 1 : Calculate the heat change/heat absorbed by the water using the formula, H = mcӨ

Changes of temperature, Ө = 59.00C - 29.00C = 30.0 0C Mass of water, m = 200 g Heat change/ heat absorbed by water , H = mcӨ c = 4.2 J g-1 oC-1

Ө = 30.0 0C H = (1)…………………………….. J

Step 2: Write a balanced chemical equation for the combustion of ethanol

C2H5OH + (2)……………= (3)……………+ (4) ……………………….

Step 3 : Calculate the number of moles of ethanol that is used in the experiment, [ Relative atomic mass : H, 1 : C,12; O,16 ]

Mass of ethanol burnt/used = (5) ………………. g Number of moles of ethanol burnt = (6) __________ molar mass of ethanol = …………………….. mol

Step 4 Calculate the heat of combustion of ethanol, ΔH

When(7) ….. mol of ethanol is burnt in oxygen heat released is(8) .……

∴ When 1 mol of ethanol is burnt in oxygen, heat released is (9) ..........

Heat of combustion of ethanol , ΔH = (10) ……………… kJ mol - 1


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Step 5 Energy level diagram

Draw an energy level diagram for the combustion of ethanol in this experiment (11)

(c) The following results are obtained by a student in an experiment to determine the heat of combustion of alcohols. Complete the table and calculate the heat of combustion of methanol, propanol and butanol based on the data given in the table below . [ Relative atomic mass : H,1 ; C,12 ; O,16 . Specific heat capacity of water , 4.2 J g-1 0C-1 ]

Alcohol Methanol

Propanol

Butanol

Volume of water/cm3 200

200 200

Initial temperature of water / 0C

28.0 28.0 28.0

Final temperature of water / 0C

60.0 58.0 59.0

Mass of alcohol burnt/g

1.184

0.750

0.719

Changes in temperature / 0C

(1) (2) (3)

Molecular formula

(4) (5) (6)

Number of carbon atoms

(7) (8) (9)

Molar mass

(10) (11) (12)

Number of moles of alcohol burnt

(13) (14) (15)

Heat change/ absorbed by the

water / J

(16) (17) (18)

Heat of combustion of alcohol /

kJ mol-1

(19) (20) (21)

(i) State the relationship between the number of carbon atoms in an alcohol and the heat of combustion, ………………………………………………………………………………………………………………. ……………………………………………………………………………………………………………….


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(ii) Predict the heat of combustion for pentanol ………………………………………………………………………………………………………………. (d) (e)

When 1 mole of butanol, C4H9OH is burnt in excess of oxygen, 2600 kJ of heat is produced. Calculate the mass of butanol needed to burn completely in oxygen in order to raise the temperature of 500 cm3 of water by 300C ( Relative atomic mass : H , 1 ; C , 12 ; O , 16, Specific heat capacity of water , 4.2 J g-1 0C-1) The heat of combustion of propanol, C3H7OH is -2016 kJ mol -1 What is its fuel value ? Solution : (i) Calculate the molar mass of propanol, C3H7OH. (ii) Calculate the fuel value of propanol, C3H7OH.

The fuel value of a fuel is the amount of heat energy given out when one gram of the fuel is completely burnt in excess of oxygen.

Fuel value ( kJ g-1 ) = heat of combustion of alcohol ( kJ mol-1 ) molar mass


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CHAPTER 5: CHEMICALS FOR CONSUMERS A : SOAP AND DETERGENT Learning Outcome:

You should be able to: state what soap is

state what detergent is

describe soap preparation process

describe the cleansing action of soap

describe the cleansing action of detergent

compare and contrast the effectiveness of the cleansing action of soap and detergent.

identify the additives in detergent and their respective functions.

Activity 1 Complete the sentences using the following words:

Surface tension, saponification, calcium, sodium, magnesium,potassium, sodium palmitate, sodium hydroxide, fat/oil ,potassium stearate, RCOO-Na+

1. Soap are……………….. or …………………… salts of long-chain fatty acids. 2. General formula of a soap is………………….. or ………………….. 3. Examples of soap are ………………………. and …………………..

4. Soap cannot be used in hard water which contains the salt of………………….. and

…………………

5. The process of the production soap is known as …………………………. 6. The two materials used to prepare soap are ………………….. and …………………..

7. When soap dissolved in water, it reduces the ……………………… of water.

Activity 2 : Preparation of soap

A. 50 cm3 of distilled water and two spatulas of table salts (sodium chloride) are added.

B. 25 cm3 of concentrated sodium hydroxide solution is added in the same beaker

C. The mixture is boiled and stirred for a few minutes

D. The mixture is boiled slowly while being stirred with a glass rod for 15 minutes


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1 Rearrange the methods for preparation of soap in the correct sequence. Then write your answers in the spaces provided.

(i) 5 cm 3 of palm oil is poured into a beaker.

(ii) ………………………………………………………………………………………… (iii) ………………………………………………………………………………………..

(iv) …………………………………………………………………………………………..

(v) ……………………………………………………………………………………………..

(vi) …………………………………………………………………………………………….. (vii) ……………………………………………………………………………………………

2. Name another substance that can be used to replace sodium hydroxide,NaOH solution in the

preparation of soap.

…………………………………………………………………………………………… 3. Why was sodium choride, NaCl used in this activity?

…………………………………………………………………………………………… 4. Write a word equation for the reaction between palm oil and sodium hydroxide.

…………………………………………………………………………………………..

E. The observations are recorded in the table provided

F. The mixture in the beaker is left to cool down and the resulting white solid is filtered

G. The following tests are carried out on the white solid: a) Touched using a finger b) Some of the white solid is shaken together with water in a test tube. c) Tested with a red litmus paper.

H. 5 cm3 of palm oil is poured into a beaker

I. The white solid that is produced is washed with a little water and dried with the filter paper


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5. Name two other substances that can be used to replace the palm oil in this activity.

…………………………………………………………………………………………..

Activity 3 Match the questions with the correct answers.

1 State an example of detergent.

White precipitate

2 What is hard water? Biological enzyme

3 Name the additive that removes organic stain.

Sodium perborate

4 What is the advantage of using detergent as a cleaning agent?

Sodium alkylbenzene sulphonate

5 Name the three materials used to prepare detergent.

Alkylbenzene,sulphuric acid and sodium hydroxide

6

State the observations when a little soap is added to hard water.

Calcium of magnesium salts of detergent are soluble.

7 An additive that prevents the fading of color.

Works effectively in hard water.

8 An additive that reduces the formation of foam.

Alkyl monoethanolamide

9 Explain why detergent can be used in hard water.

Water that contains calcium ion or magnesium ions

Activity 4: Cleansing Action of Soap and Detergent Complete the sentences by using the words in the box below

Soap /detergent reduces the ……………… of water. Hence water can wet the cloth thoroughly.

The …………………… part of the soap/detergent anion dissolves in grease.

hydrophobic , emulsion, hydrophilic, surface tension, scrubbing small droplets ,


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Activity 5 Complete tables with the correct answers. (Refer to page 182 – 186 from your text book)

DIFFERENCES BETWEEN SOAP AND DETERGENT

SOAP DETERGENT

DEFINITION ………… or potassium salts of long-chain fatty acids.

Sodium salt of..……… acid

EXAMPLES Sodium laurate ,CH3(CH2)10COONa,

…………. palmitate,

CH3(CH2)14COONa+

……………….,CH3(CH2)16COOK+

Potassium oleate, CH3(CH2)7CH=CH(CH2)7COOK+

Sodium alkyl sulphate

Sodium alkyl benzene sulphonate.

The ……………….. part of the soap/detergent is attracted to the water molecules.

The ………………… action helps to lift off the grease from the cloth.

The grease is broken into ……………… during scrubbing. These droplets remain suspended and separated as an ……………….. due to the repulsion between the negative charges on the surface


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PREPARATION NAME OF

METHOD MATERIALS

CHEMICAL EQUATION

Saponification

Palm oil, …………………….

Chemical Equation : (RCO)3(C3H5O3) (s) + 3NaOH)

(aq)

3RCOONA (aq) + C3H5(OH)3 (aq)

Sulphonation ……………….. Concentrated sulphuric

acid , long chain alcohol, sodium hydroxide.

Chemical Equation : CH3(CH2)10 CH2-O-SO3H +

NaOH CH3(CH2)10CH2-0-S-

O3Na+ + H2O

SOURCES OF RAW MATERIAL

From…………….. resources. Animal fats examples cows

and goats, vegetable oils –palm oil, olive oil and coconut oil.

Synthetic resources such

as petroleum.

EFFECTIVENESS

Soaps are effective cleaners in soft water.

Effective cleaners in both soft and …………….. water.

FORMATION OF SCUM IN HARD WATER

Hard water contains calcium

or magnesium ions. These ions react with soap to

form an insoluble precipitate known as

………………………..

Detergents do not form

scum with hard water. They form soluble

substances with calcium or …………………… ions.

EFFECT TO ENVIRONMENT

Soaps are ………………….. and do not cause any pollution.

Detergents are ………………... Detergents give thick foam that kill aquatic lives

ACTIVITY 6 : Additives in Detergent And Their Functions Complete the table below with the correct answer.

Type of additive

Example

Function.

Biological enzyme

Amylase, protease, cellulases and lipase

Sodium perborate

To convert stains into colorless substances.

Optical whitener

Fluorescent dyes


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Builder

To enhance the cleaning efficiency of detergent by softening the water

Carboxymethylcellulose (CMC)

To prevent the dirt particles removed from redepositing onto cleaned fabrics.

Filler

Sodium sulphate, sodium silicate.

Foam control agent

-

To add fragrance to both the detergent and fabrics.

Activity 7 : Cleansing Action Of Soap And Detergent (Refer to page 184 and 185 from your text book to answer the following questions) 1 The statement below is about soap and detergent.

The cleaning action of a detergent is more effective than soap in hard water.

You have two socks stained with oil. Describe briefly the experimental procedure, observations and conclusions to prove the above statement, by using substances such as soap, detergent and hard water. Procedure of the experiment: ……………………………………………………………………………………….. ……………………………………………………………………………………….. ……………………………………………………………………………………….. ………………………………………………………………………………………. ……………………………………………………………………………………….

Observations: ………………………………………………………………………………………. ………………………………………………………………………………………. Conclusions: ………………………………………………………………………………………


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……………………………………………………………………………………….

2 The following equation shows a reaction in the preparation of soap in a laboratory. Palm oil + Concentrated sodium hydroxide sodium palmitate(soap) + glycerol a) What is the name of this reaction?

……………………………………………………………………………… b) What is the homologous series of palm oil? ……………………………………………………………………………..

c) Complete the anion part of the soap particle in the space provided

3 A pupil wants to prepare potassium palmitate soap.

What alkali should he use? ……………………………………………………………………………………………….

4 Figure 2.1 shows part of the washing action of detergent particle on grease stained cloth.

i) State the part of a detergent particle that is soluble in grease.

……………………………………………………………………………………..

ii) Based on figure 2.1 explain the washing action of detergent particles on greasy stains.

…………………………………………………………………………………….. ……………………………………………………………………………………… ………………………………………………………………………………………

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2 CH2

CH2 C

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2 CH2

CH2

CH2 CH2

CH2 C

boil


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B .FOOD ADDITIVES Learning Outcomes: You should be able to

State the types if food additives and their examples.

State the functions of each type of food additives.

Justify the use of food additives.

Describe the effects of food additives on health and the environment.

ACTIVITY 8 1. A food additive is a natural or synthetic substance which is added to food

to_________________ or ____________________its appearance, ________________ or ____________________ 2. Complete the chart. 3. Complete the following table.

Type of food additive.

State the function Give two examples

To slow down the growth of microorganisms so that food can be kept for longer periods of time.

Salt, vinegar, benzoic acid.

To prevent oxidation that causes rancid fats and brown fruits

Vitamins C and E

To improve the taste of food and restore taste loss due to processing.

To prevent emulsion from separating out

To thicken food

To add or restore the color in food to enhance Its visual appeal.

Types of additives

:


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4. What are the advantages and disadvantages of using food additives?

ADVANTAGES DISADVANTAGES

5. Figure 5.6 shows a part of the label of a tin of baked beans. a) State the food additives present in the food.

b) To which type of food additives does each of the ingredients mentioned in (a) belong

Food additives present in baked beans in tomato sauce

Type of food additives

6. Sugar is used as food preservative as well as for sweetening. Patients with medical conditions such as diabetes mellitus or obesity must be wary of their intake of sugar.

a) i) Name one artificial sweetener that can replace sugar.

……………………………………………………………………………………… ii) Name one natural sweetener that can replace sugar.

………………………………………………………………………………………

b) Artificial food colorings are used in some processed foods. Suggest two reasons for using food coloring.

…………………………………………………………………………………………….. ……………………………………………………………………………………………..

Baked beans in tomato sauce Ingredients: Beans, sugar, tomato puree, salt and spice, permitted modified starch.


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C: MEDICINE

Learning Outcome


State examples of traditional medicines

State the types of modern medicines and their examples.

State the functions of each type of modern medicines

Describe the possible side effects of using modern and traditional medicines

Describe the correct usage of modern and traditional medicines.

ACTIVITY 9 Traditional medicines Complete the table below using the words in the box.

Plant Uses/function

For preventing flu attack or asthma attack. For reducing high blood pressure.

For treating stomach pain due to wind in stomach For supplying heat energy to keep the body warm.

For treating itchy skin For treating burns on the skin.

For treating boils or abscesses on the skin For preventing flu attack For treating skin diseases

For treating malaria For preventing muscle cramps

As tonic to improve the overall health of human beings For increasing energy, endurance and reducing fatigue

Has antibacterial and antifungal properties For treating coughs

As a tonic for after birth and general health To increase male libido

To treat gout, diabetes and rheumatism

To treat diarrhoe,fever and diabetes

To treat coughs colds and bronchitis.

To treat depression and for longevity

Lemon grass, lemon, garlic, aloe vera , ginseng , tongkat ali, ginger , quinine, Centella asiatica(pegaga), misai kucing, hempedu bumi,selasih,


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Activity 10 : Modern Medicines Complete the table below for classification of modern medicines and its function. (Please refer to page 198 – 201 from your text book)

Type of modern drugs Examples Uses

a) Analgesic

Aspirin

Paracetamol

Codeine

To relieve pain .……………………………… To treat headache and cough

b) ……………………..

Penicillin

Streptomycin

To cure bacterial diseases such as tuberculosis (TB) and pneumonia. …………………………………

Psychotherapeutic drugs

Stimulants : examples amphetamine, dextroamphetamine methylphenidate

Antidepressant :examples tranquilizers,

barbiturates

Antipsychotic

To reduce fatigue and elevate mood. To calm down a person and reduce tension and anxiety ……………………………….. ………………………………..

Activity 11 : Modern Medicines and Its Side Effects State one side effect for the following drugs

Type of modern drug Side effect

Aspirin

Paracetamol

Codeine

Penicillin

Streptomycin

Amphetamine

Activity 12 Answer the following questions.

1. Codeine, insulin, streptomycin and tranquilizer are examples of modern medicine. Which of

the examples is used to a) Treat diabetes mellitus?

………………………………………………………………………………….


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b) Treat pneumonia

…………………………………………………………………………………. c) Calm down the patient.

…………………………………………………………………………………. d) Relieve headache.

………………………………………………………………………………….

2. Antibiotic is a group of medicine used to kill and prevent the growth of bacteria. a) Name a disease that can be treated by antibiotic.

…………………………………………………………………………………..

b) State two examples of antibiotic

…………………………………………………………………………………..

c) Describe a good practice of taking antibiotic.

………………………………………………………………………………….

d) Explain your answer in ( c )

…………………………………………………………………………………..

3. Aspirin is an example of analgesic. a) What is an analgesic?

…………………………………………………………………………………… b) Normally aspirin is not prescribed to two groups of patient. Name the groups.

…………………………………………………………………………………… c) Explain your answer in (b)

……………………………………………………………………………………

d) Give another example of analgesic.

……………………………………………………………………………………

4. What is the use of insulin?

…………………………………………………………………………………..

5. State two differences between traditional medicines and modern medicines.

…………………………………………………………………………………… ……………………………………………………………………………………


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6. Penicillin and streptomycin are the examples of antibiotics. a) What is the function of an antibiotic?

…………………………………………………………………………………… b) Why are penicillin and streptomycin given by injection and not taken orally?

…………………………………………………………………………………….

Activity 13 1. Psychotherapeutic medicines can be classified into stimulant, antidepressant and antipsychotic. For each group in the classification, a) State its function

b) Give one example c) Give one side effect.

Psychotherapeutic medicines

Function Example Side effect

Stimulant

Antidepressant

antipsychotic

2. Suggest one proper way to manage each of the following chemicals.

Chemicals Proper management

Detergent

Food additives

Medicines


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3. Figure 3.1 shows a part of the label of a tin of sardines.

Taiping sardines

Ingredients: Fish, tomato sauce, salt, xanthan gum.

Figure 3.1 List all the food additives used in the sardines. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… 4. To which type of food additives does each of the ingredients mentioned in (a) belong? ………………………………………………………………………………………………. ………………………………………………………………………………………………. Activity 14

1 a) Diagram 1.1 shows a ginger plant. Ginger can be used as a traditional medicine.

i) Which of the parts P, Q, R or S is used as the main source of medicine? Mark ( ) for your answer in the box provided in Diagram 1.1

ii) What illness can be cured by using ginger?

……………………………………………………………………………………… iii) How is ginger used to treat the illness in 1 (a) (ii)?

………………………………………………………………………………………


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b) Table 1.1 shows the functions of three types of medicine.

Functions

Type of medicine

Prevents pain Kills or prevents the reproduction of bacteria. Changes the emotions and behavior of the patient.

X: ………………………………. Y………………………………… Z: ……………………………….

Table 1.1 i) Complete Table 1.1 to show which medicines have the functions given in the table. ii) What is the side effect of medicine of type X if it is used by a child of less than 2 years? ……………………………………………………………………………………………….. iii) A patient treated by medicine of type Y must complete all the supply given by the doctor in order to make sure all the bacteria are killed. What will happen if not all the bacteria is killed? ……………………………………………………………………………………………………. iv) Tranquilizer is an example of medicine of type Z. Give one change that might happen to a patient’s emotions when treated using this medicine. …………………………………………………………………………………………………….

modul chemistry form 5

Documents

chemical reaction

s average rate of reaction

fast reaction

slow reaction

rate of reactions

reactant time

v4 time

v3 volume of gas