Ms. Amoy Henry

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Centre Number Surname Other Names Candidate Signature

Candidate Number

For Examiner’s Use

Examiner’s Initials

Question

Mark

General Certificate of Education Advanced Level Examination January 2011

1 2 3

Chemistry
Unit 4 Kinetics, Equilibria and Organic Chemistry 9.00 am to 10.45 am Wednesday 26 January 2011

CHEM4

4 5 6 7

For this paper you must have: ● the Periodic Table/Data Sheet, provided as an insert (enclosed) ● a calculator.

TOTAL

Time allowed ● 1 hour 45 minutes Instructions ● Use black ink or black ball-point pen. ● Fill in the boxes at the top of this page. ● Answer all questions. ● You must answer the questions in the spaces provided. Do not write outside the box around each page or on blank pages. ● All working must be shown. ● Do all rough work in this book. Cross through any work you do not want to be marked. Information ● The marks for questions are shown in brackets. ● The maximum mark for this paper is 100. ● The Periodic Table/Data Sheet is provided as an insert. ● Your answers to the questions in Section B should be written in continuous prose, where appropriate. ● You will be marked on your ability to: – use good English – organise information clearly – use accurate scientific terminology. Advice ● You are advised to spend about 70 minutes on Section A and about 35 minutes on Section B.

(JAN11CHEM401)

WMP/Jan11/CHEM4

CHEM4

2 Section A Answer all questions in the spaces provided.

Do not write outside the box

1

The rate of hydrolysis of an ester X (HCOOCH2CH2CH3) was studied in alkaline conditions at a given temperature. The rate was found to be first order with respect to the ester and first order with respect to hydroxide ions. Name ester X. ............................................................................................................................................ (1 mark)

1 (a) (i)

1 (a) (ii) Using X to represent the ester, write a rate equation for this hydrolysis reaction. ............................................................................................................................................ (1 mark) 1 (a) (iii) When the initial concentration of X was 0.024 mol dm–3 and the initial concentration of hydroxide ions was 0.035 mol dm–3, the initial rate of the reaction was 8.5 x 10–5 mol dm–3 s–1. Calculate a value for the rate constant at this temperature and give its units. Calculation ......................................................................................................................... ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ Units .................................................................................................................................. ............................................................................................................................................ (3 marks) 1 (a) (iv) In a second experiment at the same temperature, water was added to the original reaction mixture so that the total volume was doubled. Calculate the initial rate of reaction in this second experiment. ............................................................................................................................................ ............................................................................................................................................ (1 mark)

(02)

WMP/Jan11/CHEM4

3 1 (a) (v) In a third experiment at the same temperature, the concentration of X was half that used in the experiment in part 1 (a) (iii) and the concentration of hydroxide ions...
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