TGS 2020 CHEMISTRY HOLIDAY PACKAGE 1

TORORO GIRLS’ SCHOOL

SENIOR SIX CHEMISTRY REVISION TEST

PAPER ONE

2 HOURS AND 45 MINUTES

Instructions

Attempt all questions in section A

Attempt any six questions from section B.

All answers must be shown in the spaces provided.

SECTION A

Attempt all questions in this section

1. Propanoic acid is a weak acid with acid dissociation constant of

1.34 × 10−5 𝑎𝑡 250𝐶 (a) Write the equation for the ionization of propanoic acid in water.

(1 mark)

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(b) Calculate the pH of a solution prepared by dissolving 100 cm3 of 0.2M

propanoic acid solution into 400 cm3 of water. (4 marks)

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TGS 2020 CHEMISTRY HOLIDAY PACKAGE 2

2. State the observation and write equation for the reaction between zinc

sulphate solution and; -

(a) Sodium hydroxide solution. (3 ½ marks)

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(b) Ammonia solution. (2 ½ marks)

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3. An organic compound K with molecular formula C3H6 decolorizes bromine

water.

(a) Identify K. (1 mark)

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(b) Write equation leading to the formation of K from an alcohol. (1 mark)

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(c) Write a mechanism for the reaction between K and bromine water.

(2 ½ marks)

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TGS 2020 CHEMISTRY HOLIDAY PACKAGE 3

4. (a) Define colligative property. (1 mark)

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(b) Apart from freezing point depression state two other colligative

properties. (1 mark)

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(c) When 0.258g of a benzoic acid was dissolved in 40g of benzene the

freezing point of the solution was lowered to 5.230C. calculate the molecular

weight of benzoic acid. (4 marks)

[freezing point constant of benzene is 5.12, freezing point of pure benzene is 5.50C]

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5. (a) Define first ionization energy. (1 mark)

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(b) The table below shows the first four ionization energies of an element

X.

1st 2nd 3rd 4th

Energy/kjmol-1 737.75 1450.6 7732.68 10542.51

TGS 2020 CHEMISTRY HOLIDAY PACKAGE 4

Giving reason state the group in the periodic table to which element X

belongs. (3 marks)

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6. The table below shows the standard electrode potentials for two electrodes A

and B.

Electrode. Electrode potential/volts

A 𝐻𝑔2+/𝐻𝑔 +0.86V

B 𝑅𝑏+/𝑅𝑏 -2.93

(a) (i) Write the cell notation of the cell formed when the half cells A and B

are combined. (1 ½ marks)

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(ii) Calculate the electromotive force for the cell formed in a(i) above.

(1 ½ marks)

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(b) Draw a set up for the apparatus used to determine the standard electrode

potential for the electrode A using the standard hydrogen electrode in the

laboratory. (4 marks)

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TGS 2020 CHEMISTRY HOLIDAY PACKAGE 5

7. (a) Write the possible chemical formula of the oxides of lead. (1 ½

marks)

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(b) Write equations for the reaction between nitric acid and the oxides in

7(a) above. (4 ½ marks)

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8. Element iron is a transition metal.

(a) Write the electronic configuration of iron. (1 mark)

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(b) State three properties in which iron behaves as a transition metal.

(1 ½ marks)

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(c) To a mixture containing sodium nitrite and iron (II) sulphate was added

concentrated sulphuric acid.

(i) State what was observed? (1 mark)

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(ii) Write equation for the reaction which took place. (1 ½ marks)

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TGS 2020 CHEMISTRY HOLIDAY PACKAGE 6

SECTION B

Attempt any six questions

9 . (a) Define structural isomerism. (1 mark)

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(b) Using the molecular formula 𝐶3𝐻6𝑂, write a pair of strutures and their corresponding names which are:

(i) Position isomers. (4 marks)

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(ii) Functional isomers. (4 marks)

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TGS 2020 CHEMISTRY HOLIDAY PACKAGE 7

9. (a) Define hydrolysis. (1 mark)

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(b) Write the equation for the hydrolysis of sodium benzoate in water.

(1 ½ marks)

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(c) Calculate the pH of a solution formed when 25 cm3 of 0.1M sodium

hydroxide solution is mixed with 25 cm3 of 0.1M benzoic acid at 250C

(5 ½ marks)

[the acid dissociation constant of benzoic acid is 6.3 × 10−5]

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10. (a) State the principle of steam distillation. (3 marks)

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TGS 2020 CHEMISTRY HOLIDAY PACKAGE 8

(b) State two properties of a substance which allow it to be separated by

steam distillation. (2 marks)

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(c) When a compound Q with relative molecular mass of 120 is steam

distilled, the mixture boils at 980C. the vapor pressure of water is 94300𝑁𝑚−2 . At

this temperature the atmospheric pressure is 100900𝑁𝑚−2, calculate the composition by mass of the distillate. (4 marks)

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11. 34g of an organic compound which contains carbon, hydrogen and nitrogen

with relative molecular mass 170 burnt in excess oxygen to give 52.8g of

carbon dioxide and 12.6g of water.

(a) Calculate the molecular formula of M (4 marks)

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(b) Compound M reacts with nitrous acid to give a compound which forms a

red solid with 2-Napthol. Identify M. (1 mark)

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TGS 2020 CHEMISTRY HOLIDAY PACKAGE 9

(c) Write equation for the ioniation of M in water. (1 mark)

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(d) Using equations show how compound M can be synthesized from

benzene. (3marks)

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12. (a) Define enthalpy of neutralization. (1 mark)

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(c) a reaction of 100 cm3 1.35M hydrochloric and 100 cm3 of 1.76M sodium

hydroxide is monitored and the following temperatures were recorded.

Staring temperature 24.60C and final temperature 38.80C.

Calculate;

(i) Number of moles of hydrochloric acid that reacted. (1 mark)

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(ii) Number of moles of sodium hydroxide that reacted (1 mark)

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TGS 2020 CHEMISTRY HOLIDAY PACKAGE 10

(iii) Heat of neutralization for the reaction. (6 marks)

[density of solution is 1gcm-3 and specific heat capacity of solution is 4.2jg-1k-1]

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13. State the conditions and write equation(s) for the reaction between;

(a) Fluorine and sodium hydroxide. (3 marks)

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(b) Chlorine and sodium hydroxide (3 marks)

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(c) Aluminum nitrate solution and sodium carbonate. (3 marks)

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TGS 2020 CHEMISTRY HOLIDAY PACKAGE 11

14. Complete each of the following equations and write a mechanism for the

reaction.

(2 marks)

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(4 marks)

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(3 marks)

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TGS 2020 CHEMISTRY HOLIDAY PACKAGE 12

15. A salt Z dissolved in water to give a violet solution which reacts with

sodium hydroxide solution to give a green precipitate. the green precipitate

dissolves in excess sodium hydroxide to give a green solution. Salt Z

decomposes on heating to give a solid and a brown gas.

(a) Identify Z. (1 mark)

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(b) Write the equation for the decomposition of Z on heating. (1 ½ mark)

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(c) Write equation and state the observation for the reaction between Z and

ammonia solution. (4 ½ marks)

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(d) To the solution of Z was added ammonia a solution. State what was

observed and write the equation(s) for the reaction. (2 marks)

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16. (a) Distinguish between addition polymerization and condensation

polymerization. (2 marks)

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TGS 2020 CHEMISTRY HOLIDAY PACKAGE 13

(b) Write the structural formula(s) and name of the monomers for each of

the following polymers.

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(b) State the use of the polymer in b(i) above. (1 mark)

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