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Index Number:

MINISTRY OF EDUCATION

FIJI SEVENTH FORM CERTIFICATE EXAMINATION 2010

CHEMISTRY PAPER 2

QUESTION AND ANSWER BOOK

Time Allowed: One Hour

(An extra ten minutes is allowed for reading this paper.)

HAND IN THIS QUESTION AND ANSWER BOOK TO THE SUPERVISOR BEFORE YOU LEAVE THE EXAMINATION ROOM.

INSTRUCTIONS

1. Write your Index Number at the top of this page and inside the back flap of this Question and Answer Book.

2. Write your answer to each question in the space provided in this book.

3. Answer all the questions with a blue or black ballpoint or ink pen. Do not use red ink. Use a pencil only for drawing.

4. If you use extra sheets of paper, be sure to write clearly the question number(s) being answered and to tie each sheet securely in this book in the appropriate places.

5. You may use a calculator, provided it is silent, battery-operated and non-programmable.

6. There are eight questions altogether in this paper. All the questions are compulsory and each one is worth five marks.

7. Spend approximately seven minutes on each question.

8. Before handing in this Question and Answer Book, make sure that your Index Number is at the top of this page and inside the back flap.

Note : A Periodic Table of Elements is provided for your use during this examination. Both the atomic number and the relative atomic mass for each element are given.

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2.

QUESTION 1

The diagram given below shows some examples of bad laboratory practice.

Identify five laboratory practices that you consider to be dangerous and state the correct procedure that should be followed.

(i) __________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________ (1 mark)

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3.

(ii) __________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________ (1 mark)

(iii) __________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________ (1 mark)

(iv) __________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________ (1 mark)

(v) __________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________ (1 mark)

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4.

QUESTION 2

(a) The diagrams given below show various pieces and sets of equipment you have used in the science laboratory during the year.

Which piece or set of equipment (A – J) would be used for the following purposes?

(i) Remove immiscible liquids from a mixture. (1 mark)

(ii) Remove the water of crystallisation from magnesium heptahydrate. (1 mark)

(iii) Measure volume of a gas. (1 mark)

(iv) Prepare 200 mL of a known solution of potassium permanganate. (1 mark)

(v) Carry out vaccum filteration. (1 mark)

© MINISTRY OF EDUCATION, FSFCE 2010: CHEMISTRY.

5

A. B. C. D.

E. F.

J.

H. I.

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5.

QUESTION 3

(a) Consider the illustration given below and answer the questions that follow.

(i) What can you conclude from the above observation?

____________________________________________________________________

____________________________________________________________________ (1 mark)

(ii) Account for the conclusion made in (i) above.

____________________________________________________________________

____________________________________________________________________ (1 mark)

(b) (i) Use your knowledge of practical work on the properties of molecules to complete the table given below.

Solute Nature of Solute

Solubility in

CCl4 CH3OH H2O

Naphthalene 1.__________ soluble 2.__________ 3.__________

Potassium

chloride ionic 4.__________ insoluble 5.__________

(2½ marks)

(ii) What type of solvent is generally best suited to dissolve ionic and highly polar substances?

____________________________________________________________________ (½ mark)

5 ice cube

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6.

QUESTION 4

(a) An experiment was carried out to measure the heat of solution of anhydrous magnesium sulphate and magnesium sulphate heptahydrate as shown in the diagrams given below.

The change in temperature was recorded in the table as follows:

Anhydrous magnesium sulphate

Magnesium sulphate heptahydrate

Initial temperature (°C) 26 26

Final temperature (°C) 32 24

(i) Name the special piece of apparatus that could be used instead of the apparatus shown above.

____________________________________________________________________ (½ mark) (ii) Calculate the temperature change for the exothermic reaction.

____________________________________________________________________

____________________________________________________________________ (1 mark)

stirrer _stirrer

thermometer thermometer

conical flask conical flask

water and anhydrous

magnesium sulphate

water and

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(iii) Why is the enthalpy change for MgSO4(s) + 7 H2O(l) MgSO4.7 H2O(s)

difficult to measure directly?

____________________________________________________________________

____________________________________________________________________ (1 mark)

(iv) What is the source of heat energy in the reaction of anhydrous magnesium sulphate?

____________________________________________________________________

____________________________________________________________________ (1 mark)

(v) Write one possible source of error in this experiment.

____________________________________________________________________ (½ mark)

(b) Warning symbols are often placed on containers of chemicals. For each of the symbols given below, write the meaning of the symbol.

__________________________________________ (½ mark)

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8.

QUESTION 5

In a laboratory experiment 10 g of 2-methylpropan-2-ol was allowed to react with concentrated hydrochloric acid for 15 minutes.

The reaction mixture separated into two layers and the lower aqueous layer was separated off and discarded.

The upper layer was washed with sodium bicarbonate solution. A gas was evolved during this operation. The lower aqueous layer was again separated off and discarded.

The organic layer was shaken with anhydrous sodium sulphate crystals, the mixture was allowed to stand for 30 minutes, and then filtered off. The organic liquid was then distilled.

The main fraction which boiled between 49°C and 52°C weighed 11 g.

[M(CH3)3COH = 74 gmol-1 ; Ar (Cl) = 35.5]

(i) Draw the structural formula and give the systematic name of the organic product.

Structural formula: __________________________________________________________

__________________________________________________________________________

__________________________________________________________________________ (½ mark) Name: ____________________________________________________________________

(½ mark)

(ii) Name the equipment that could be used to separate the lower aqueous layer from the mixture.

__________________________________________________________________________ (½ mark)

(iii) Identify the gas produced during the washing operation.

__________________________________________________________________________ (½ mark)

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(iv) What impurities are removed by washing the product with sodium bicarbonate solution?

__________________________________________________________________________ (½ mark) (v) What is the purpose of anhydrous sodium sulphate crystals?

__________________________________________________________________________

__________________________________________________________________________ (½ mark) (vi) What percentage of the total possible yield of the product was obtained?

__________________________________________________________________________

__________________________________________________________________________ (2 marks)

QUESTION 6

(a) For each of the following reactions, state one observation that you will make when:

(i) heating a mixture of propanol and propanoic acid in the presence of a few drops of concentrated sulphuric acid.

____________________________________________________________________

____________________________________________________________________ (1 mark)

(ii) 3 drops of bromine solution are shaken with but-2-ene.

____________________________________________________________________

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(iii) butan-2-one is added to a mixture of iodine solution and sodium hydroxide solution.

____________________________________________________________________

____________________________________________________________________ (1 mark)

(b) Explain why the air-hole is usually closed when a lighted burner is not in use.

__________________________________________________________________________

__________________________________________________________________________ (1 mark)

(c) Explain why transition metals are more important than the regular metals in catalysis.

__________________________________________________________________________

__________________________________________________________________________ (1 mark)

QUESTION 7

(a) The pH of a 0.10 mol L-1 sample of an organic acid, 2-methylbutanoic acid, (CH3)2 CHCOOH is 3.0.

(i) Write the equation for the acid dissociation of 2-methylbutanoic acid, and then the expression for the acid dissociation constant, Ka.

____________________________________________________________________

____________________________________________________________________ (1½ marks)

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11.

(ii) Calculate the Ka value of 2-methylbutanoic acid.

____________________________________________________________________

____________________________________________________________________ (1½ marks)

(b) The boiling points of the four isomers of butene are:

but-l-ene - - 6.3°C cis-but-2-ene - 37°C trans-but-2-ene - 0.88°C 2-methylpropene - - 6.9°C

(i) What does this table tell you about isomerism?

____________________________________________________________________

____________________________________________________________________ (1 mark)

(ii) Suggest a reason why 2-methylpropene has the lowest boiling point.

____________________________________________________________________

____________________________________________________________________ (1 mark)

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12.

QUESTION 8

Consider the electrochemical cell notation and the standard electrode potentials given below. Ag , Ag / Ag / / Ni / Ni ,

Ni ₍_s₎ ₍2_aq₎ ₍_aq₎ ₍_s₎

V 25 . 0 E Ni / Ni V 80 . 0 E Ag / Ag 2

(i) Draw a labelled diagram of the cell based on the given cell notation. Show clearly the anode, cathode and the direction of electron flow.

(2 marks)

(ii) Write the equation for the spontaneous cell reaction.

__________________________________________________________________________

__________________________________________________________________________ (1 mark)

(iii) Calcualte the emf (E_cell)of the cell.

__________________________________________________________________________

__________________________________________________________________________ (1 mark)

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(iv) If the silver electrode is replaced by a copper electrode, would the reaction be spontaneous? Support your answer with relevant calculation.

] V 34 . 0 E

Cu / Cu [ 2

__________________________________________________________________________

(1 mark)

THE END

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INDEX NUMBER

CHEMISTRY PAPER 2 FOR MARKER’S USE

Ques.

No.

Marks

Gained Check

Mark

1

2

3

4

5

6

7

8