CE Chemistry ~ Paper I

by Alan Cheng

F.5 Chemistry Mock Examination Prepared by Alan Cheng

© by Alan Cheng

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F.5 Chemistry Mock Examination Prepared by Alan Cheng

© by Alan Cheng

Section A Answer ALL questions. Write your answers in the spaces provided. 1. The following table gives some information about particles W, X, Y and Z.

Number of proton Number of neutron Mass number W 18 35 X 12 24 Y 17 20 Z 22 40

(a) Which TWO of the above elements would form an ionic compound? Draw the electronic

structure of the compound formed. (Showing electrons in the outermost shell only.) (b) In which group of the Periodic Table would X be placed? Explain your answer. (c) (i) State the relationship between element W and Y.

(ii) Do molecules of W and Y have the same chemical properties? Explain your answer. (iii) Write a chemical equation for the reaction between molecule of W and dilute

sodium hydroxide solution. (7 marks)

2. The flow diagram below shows some reactions about metal A. (a) (i) Name metal A.

(ii) Write the chemical reaction between metal A and dilute hydrochloric acid. State whether it is a redox reaction or not. Explain your answer in term of the change in oxidation number.

(b) Solution B react with aqueous ammonia to form a precipitate iron(II) hydroxide.

(i) State the colour of the precipitate. (ii) Write the chemical reaction between solution B and aqueous ammonia.

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F.5 Chemistry Mock Examination Prepared by Alan Cheng

© by Alan Cheng

(c) If calcium is added to solution B, metal A and colourless gas bubbles formed.

(i) Name the type of reaction for the formation of metal A. (ii) Why is a colourless gas formed?

(8 marks) 3. But-1-ene molecules polymerize to form a polymer. (a) State the type of polymerization for the formation of this polymer. Explain your answer. (b) Draw the repeating unit and write the equation to show the formation of the polymer. (c) Calculate the number of repeating units in this polymer if it has a relative molecular

mass of 196000. (6 marks) 4. The diagram below shows an industrial plant of oil refinery. (a) Why is crude oil referred to as a “fossil” fuel? (b) Why can the various petroleum fractions be obtained from crude oil by fractional

distillation? (c) Different fractions are obtained from crude oil under high temperature and absence of

air. (i) Explain why the process must undergo in the absence of air? (ii) Explain whether the product from B or F has a higher boiling point.

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F.5 Chemistry Mock Examination Prepared by Alan Cheng

© by Alan Cheng

(d) Liquefied petroleum gas (LPG) consists mainly of butane. (i) State the fraction from which LPG come from. (ii) Write a chemical equation for the complete combustion of butane.

(6 marks) 5. For each of the following experiments, state an expected observation and write a

chemical equation for the reaction involved. (a) Adding dilute hydrochloric acid to lime. (b) Bromine water is added to potassium iodide solution. (c) Sodium sulphite solution is added to acidified potassium dichromate solution.

(6 marks) 6. A student says:

“Both sodium chloride solution and ethanol are electrolyte because they can ionize in water to give mobile ions.”

State whether the above statements is true or false. Explain your answer.

(3 marks) 7. The flow diagram below shows the industrial process of manufacture of sulphuric acid. (a) Name the process. (b) Suggest ONE method for each to produce the following gases required for the process. (i) sulphur dioxide (ii) oxygen

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F.5 Chemistry Mock Examination Prepared by Alan Cheng

© by Alan Cheng

(c) In stage I, a catalyst is needed for the conversion of sulphur dioxide to sulphur trioxide. (i) name the compound that should be used as the catalyst.

(ii) explain why the sulphur dioxide and oxygen should be dried and purified before the reaction.

(d) The sulphuric acid obtained by this industrial process contains 96% by mass of

sulphuric acid and has a density of 1.84 g cm-3. Calculate the molarity in “mol dm-3” of the sulphuric acid.

(e) Give ONE use of sulphuric acid in industry. (9 marks) For question 8, candidates are required to give a paragraph-length answer. In this question, 6 marks will be awarded for chemical knowledge and 3 marks for effective communication. 8. Both Sulphur dioxide and carbon dioxide are colourless gases. Discuss the similarities

and differences in chemical properties of these two gases. Illustrate your answer using appropriate examples.

(9 marks)

END OF SECTION A

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F.5 Chemistry Mock Examination Prepared by Alan Cheng

© by Alan Cheng

SECTION B

Answer ALL questions. Write your answers in the space provided. 9. Consider the set-up shown below:

A, B, C and D are four electrodes. A, B and D are made of copper while C is made of zinc.

(a) State which electrodes are the anodes? (b) State the direction of electron flow between electrode A and electrode D.

(c) The salt bridge is a filter paper soaked with a saturated solution.

(i) What is the meaning of the term “saturated solution”? (ii) State the function of the salt bridge.

(d) A student says: “Sodium can be used for electrode C instead of zinc to give a higher

voltage.” Explain whether his answer is true or false.

(e) When the circuit is closed for several minutes, the mass of electrode B increase. (i) Write chemical equations for the reaction occur in electrode A and B.

(ii) State the colour change of the copper (II) sulphate solution. (9 marks)

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F.5 Chemistry Mock Examination Prepared by Alan Cheng

© by Alan Cheng

10. The following structure represents a soapy detergent and a polymer.

CH3 CH2

CH2

CH2 CH2

CH2

CH2

CH2CH2CH2CH2

CH2 C

O

ONa

N N CC

O OHH

n

soapy detergent

polymer X

(a) The soapy detergent is said to be “biodegradable”. State ONE harmful effect on the environment if a detergent is non-biodegradable.

(b) Explain why soapy detergent does not function well in hard water

(c) The soapy detergent can be prepared in the school laboratory from vegetable oil.

Briefly describe the experimental procedure for its preparation.

(d) Polymer X is a condensation polymer which made by two monomers. (i) Draw the structures of the monomers of polymer X.

(ii) What is meant by the term “condensation polymer”? (9 marks)

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F.5 Chemistry Mock Examination Prepared by Alan Cheng

© by Alan Cheng

11. A student carried out the following experiment to determine the purity of citric acid (a

tribasic acid with a relative molecular mass of 192) in a sample of vitamin tablet. The experiment consisted of the following procedures:

2.5 g of the vitamin tablet powder dissolved in distilled water and made up to 250 cm3. 25 cm3 of the diluted solution was withdrawn to a conical flask and titrated against 0.1 M sodium hydroxide solution.

(a) Name the apparatus that should be used to transfer 25 cm3 of the diluted sample

to the conical flask.

(b) Suggest a suitable indicator for the titration and state the colour change at the end point.

The student carried out four titrations altogether. The titration results are listed in the table below:

Titration Burette reading

1 2 3 4

Final reading / cm3 12.5 13.7 17.1 21.6

Initial reading / cm3 0.0 2.2 5.5 10.2

(c) (i) Based on the titration results, calculate a reasonable average for the volume of

the sodium hydroxide solution used. (ii) Calculate the mass of citric acid in the tablet.

(iii) Determine the percentage purity of citric acid in the sample. (9 marks)

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F.5 Chemistry Mock Examination Prepared by Alan Cheng

© by Alan Cheng

For question 12, candidates are required to give a paragraph-length answer. In this question, 6 marks will be awarded for chemical knowledge and 3 marks for effective communication. 12. A student has six unlabelled bottles and each contains one of the following colourless

chemicals:

Ethanol 1 M ethanoic acid 1 M potassium hydroxide solution kerosene 1 M nitric acid 1 M sodium sulphate solution

Suggest how he would carry out chemical tests to identify the contents of each bottle, using the materials and apparatus listed below. Your answer should include the observation of each test.

Acidified potassium dichromate solution, 1 M iron (III) nitrate solution, magnesium ribbon, 1 M calcium nitrate solution, test tubes and a Bunsen burner

(You are NOT required to write chemical equations. Answers in the form of flow diagrams will NOT be marked)

(9 marks)

END OF PAPER

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