Centre Candidate Number

Page 1 of 13
Number

Candidate Name ____________________________

MCM NKANA SECONDARY SCHOOL

Exam Practice for School Certificate Ordinary Level

Chemistry 5070//2
Paper 2 Theory

Wednesday 4th November, 2020

Additional materials:

Mathematical tables/Calculators (non programmable)

Time: 2 hours

Instructions to Candidates

Write your name, centre number and candidate number in the spaces at the top of this page.
There are twelve (12) questions in this paper
Section A
Answer all questions.
Write your answers in the spaces provided on the question paper.
Section B

Answer any three questions.

Write your answers in the separate answer sheets provided Candidate’s use Examiner’s use
and fasten. Section A
INFORMATION FOR CANDIDATES Section B 9

The number of marks is given in brackets [ ] at the end of

each question or part question. Candidates are reminded that 10
all quantitative answers should include appropriate units. Tick
the questions answered in section B in the grid.
11
Candidates are advised to show all their working in a clear
and orderly manner, as more marks are awarded for correct
working than for correct answers. 12

Cell phones are not allowed in the examination room Total

©MCM/EP/2020
This question paper consists of 13 printed pages.

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Section A [50 Marks]

Answer all the questions in the spaces provided on the question paper.

A1 (a) One of the laboratory rules read as follows:

DO NOT EAT ANYTHING IN THE LABORATORY

(i) Explain why this rule is important

…………………………………………………………………………………………

…………………………………………………………………………………………

(ii) State one other laboratory safety rule.

…………………………………………………………………………………………

……………………………………………………………………………………….. [3]

(b) Important skills which a chemist needs to have include correct measurement of quantities

and choosing correct pieces of apparatus/equipment for carrying out some experimental

procedures. State the name of a piece of apparatus which can be used to:

(i) Measure accurately a volume of 0.6cm3.

…………………………………………………………………………………..

(ii) Measure the mass of a cooking oil sample.

………………………………………………………………………………….

(iii) Hold 50cm3 of solution during a chemical reaction.

…………………………………………………………………………………. [3]

[Total 6]

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A2 The graph below shows a heating curve for pure substance. The temperature rises with

time as the substance is heated.

(a) What physical state(s) is the substance in at A and C?

State at A: …………………………………………………………….

State at C: ……………………………………………………………. [2]

(b) Describe the movement of the particles of the substance at A and C.

Movement at A: ……………………………………………………………….

………………………………………………………………

Movement at C: ……………………………………………………………….

……………………………………………………………….. [2]

(c) What is the melting point and boiling point of the substance?

Melting point: …………………………………………………………………..

Boiling point: ………………………………………………………………….. [2]

(d) Describe what happens to the temperature while the substance is changing its physical
state.

………………………………………………………………………………………

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……………………………………………………………………………………. [1]

[Total 7]

A3 The diagram below shows the structures of atoms of two elements A and B.

(a) State the Group and Period number of each of the two elements A and B.

A Period……………………………… Group …………………………

B Period……………………………… Group ………………………… [2]

(b) If atoms of element A and element B combined to form a compound, what type of
bonding would be involved? Using electron-shell diagram draw the structure of the
compound formed between A and B.

Type of bonding: ……………………………………………………………

Structure of compound:

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[3]

[Total 5]

A4 A sample of iron filling had partly rusted upon being left under damp conditions. 3.5g of

Iron filling were added to 50cm3 of aqueous copper (II) sulphate. All the copper in copper (II)

Sulphate was displaced according to the equation below.

CuSO4(aq) + Fe(s) Cu(s) + FeSO4 (aq)

3.2 g of copper was formed.

(a) Write the ionic equation for the above reaction.

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

……………………………………………………………………………………………………… [1]

(b). If neither the iron nor the copper (II) sulphate was in excess, calculate

(i) the mass of iron which was present in the iron fillings sample.

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[3]

(ii). The percentage by mass of rust in the iron fillings sample.

[2]

(iii) The concentration of the copper (II) sulphate solution in moles per dm3

[3]
[Total 9]

A5 Lithium, sodium, potassium and rubidium are members of Group I of the Periodic Table.

(a) What is the common name given to Group I elements?

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………………………………………………………………………………………. [1]

(b) State any two physical properties of group I elements.

………………………………………………………………………………………..

……………………………………………………………………………………….. [2]

(c) Lithium reacts with water to form lithium hydroxide and hydrogen gas. Write the
balanced chemical equation for this reaction.

…………………………………………………………………………………………..

………………………………………………………………………………………….. [2]

(d) How would be the speed of reaction of lithium with water compare with that of rubidium
with water?

…………………………………………………………………………………………….

……………………………………………………………………………………………... [1]

[Total 6]

A6 Hydrogen reacts with chlorine to make hydrogen chloride. The reaction is exothermic. The
reaction can be represented by the equation below.

H-H + Cl-Cl H-Cl + H-Cl ∆H= -184 kJ/mol

(a) A mixture of 2.5 g of hydrogen and 142 g of chlorine is allowed to react.

(i) Which gas, hydrogen or chlorine, is in excess? Explain your answer .

…………………………………………………………………………………………

…………………………………………………………………………………………

…………………………………………………………………………………………

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(ii) Calculate the energy released when 2.5 g of hydrogen reacts completely with
chlorine gas.

[3]
(b) Explain why the reaction is exothermic, in terms of the energy changes that takes place
during bond breaking and bond making.

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

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

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

……………………………………………………………………………………………………[3]

(c) Nitrogen reacts with oxygen to form nitrogen (II) oxide. The energy profile diagram for
the reaction is shown below.

(i) Is the reaction exothermic or endothermic? Explain your answer.

………………………………………………………………………………………………

…………………………………………………………………………………………….

(ii) Label on the diagram the activation energy for the reaction. [2]

[Total 8]

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A7 Choose from the following metals to answer the questions below.

Aluminium calcium copper iron

Magnesium potassium sodium zinc

Name a metal which

(a) Is manufactured by electrolysis of its molten oxide.

……………………………………………………………………………………. [1]

(b) Has a variable valency,

……………………………………………………………………………………… [1]

(c) Is used to galvanise iron,

………………………………………………………………………………………. [1]

(d) Has a carbonate which is coloured,

……………………………………………………………………………………… [1]

(e) Is alloyed with zinc to make brass

……………………………………………………………………………………… [1]
[Total 5]

A8 Nitrogen dioxide is an atmospheric pollutant.

(a) One source of nitrogen dioxide in the air is from the gases from car engines. Explain
how nitrogen dioxide is formed in a car and indicate how its emission can be limited.

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

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

…………………………………………………………………………………………………

……………………………………………………………………………………………… [2]

(b) Name any other two atmospheric pollutant.

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i. …………………………………………………………………………………

ii. ………………………………………………………………………………… [2]

[Total 4]

Section B (30 marks)

Answer three questions from this section.

Write your answers in the Answer on the separate answer sheet.

B9. (a) Sodium sulphate is a soluble salt that can be prepared from dilute sulphuriic acid.

i. Name the other chemical that can be reacted with dilute sulphuric acid to prepare
the salt. [1]
ii. Write a balanced chemical equation with state symbols for the reaction above. [2]
iii. Describe in detail how you would prepare pure crystals of sodium sulphate using
the named reactants. [4]
(b). The salt prepared is a normal salt.

i. What is a normal salt? [1]

ii. If the above reactants were to form an acid salt, give the name of the acid salt
that would be formed from the two reactants and give the chemical formula. [2]
[Total 10]

B10 An excess of zinc was added to 10 cm3 of 0.5 mol/dm3 hydrochloric acid, using the
apparatus below

(a) Calculate the maximum volume of hydrogen which could be produced in the reaction at

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r.t.p. [3]

The graph shows how the volume of hydrogen changed during the reaction.

(b) (i) Describe how the rate of reaction of reaction changes as the reaction progresses

(ii). Suggest a reason for this change [2]

(c) The experiment was repeated using dilute sulphuric acid of the same concentration.

Write a balanced equation for the reaction between zinc and sulphuric acid.

Suggest how both the rate of reaction and total volume of hydrogen obtained would
differ from the reaction between zinc and hydrochloric acid.
[5]
[Total 10]

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B11 The diagram below shows apparatus used in the silver-plating of an iron article. During the
electroplating, a current of 5A was passed through the aqueous electrolyte for 8.0 minutes.

(a) (i) What is meant by electroplating?

(ii) State one reason why electroplating is used. [2]

(b) State the names of electrode X electrolyte Y which must be used in order for successful
plating to occur. [2]
(c) Write equations for the reactions occurring at the electrodes. [1]
(d) What mass of silver is deposited on the iron article? [2]
(e) If the iron article was to be coated with copper instead silver, State the materials needed
to be used for electrode X and electrolyte Y. [1]
(f) State two applications of electrolysis. [2]
[Total 10]

B12 The table shows the first four members of a particular homologous series.

Compound Molecular formula Relative Molecular mass

Methanol CH3OH 32

Ethanol C2H5OH 46

Propanol C3H7OH 60
Butanol C4H9OH ?

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(a) (i) Name the homologous to which these compounds belong. [1]

(ii) Deduce the general formula of this homologous series. [1]

(iii) State the Relative formular mass of butanol. [1]

(b) Ethanol is manufactured from either ethane or glucose.

(i) Construct an equation for the production of ethanol from ethane using structural
formulae. [2]

(ii) state the conditions necessary for the reactions in b(i) above. [1]

(iii) The fermentation of glucose can be represented by the following equation.

C6H12O6 2C2H5OH + 2CO2

Calculate the maximum mass of ethanol that can be made from 72 tonnes of Glucose. [3]

[Total 10]

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