Chemistry 9701/42 — May/June 2013

Cambridge A-Level · A Level Structured Questions · worked solutions for every part, with the mark scheme

questions

100

marks

120

minutes

Topics Halogen Compounds · Hydroxy Compounds · Transition Elements · Carboxylic Acids and Derivatives · Hydrocarbons · Nitrogen Compounds · +6 more

Q1Halogen CompoundsReaction KineticsFree sample

A bromoalkane, R–Br, is hydrolysed by aqueous sodium hydroxide.

(a)

(i)

Write a balanced equation for this reaction.

(ii)

What type of reaction is this?

(b)

The concentration of bromoalkane was determined at regular time intervals as the reaction progressed.

Two separate experiments were carried out, with different $\text{NaOH}$ concentrations.

The graph below shows the results of an experiment using $[\text{NaOH}] = 0.10 \text{ mol dm}^{-3}$ .

Fig. 1.1

When the experiment was repeated using $[\text{NaOH}] = 0.15 \text{ mol dm}^{-3}$ , the following results were obtained.

time / min	[R–Br] / $\text{mol dm}^{-3}$
0	0.0100
40	0.0070
80	0.0049
120	0.0034
160	0.0024
200	0.0017
240	0.0012

(i)

Plot these data on the axes above, and draw a line of best fit.

(ii)

Use one of the graphs to confirm that the reaction is first order with respect to R–Br. Show all your working, and show clearly any construction lines you draw.

(iii)

Use the graphs to calculate the order of reaction with respect to $\text{NaOH}$ . Show all your working, and show clearly any construction lines you draw on the graphs.

(iv)

Write the rate equation for this reaction, and calculate the value of the rate constant.

\text{rate} =

(c)

Nitric oxide, $\text{NO}$ , and bromine vapour react together according to the following equation.

2\text{NO(g)} + \text{Br}_2\text{(g)} \rightarrow 2\text{NOBr(g)} \quad \Delta H = -23 \text{ kJ mol}^{-1}

The reaction has an activation energy of $+5.4 \text{ kJ mol}^{-1}$ .

Use the following axes to sketch a fully-labelled reaction pathway diagram for this reaction.
Include all numerical data on your diagram.

Fig. 1.2

The rest of this paper

7 more questions

Q2Electrochemistry · Transition Elements · Equilibria · Carboxylic Acids and Derivatives17M
Q3Hydrocarbons · Hydroxy Compounds · Nitrogen Compounds11M
Q4Transition Elements14M
Q5Introduction to A Level Organic Chemistry · Hydroxy Compounds · Carboxylic Acids and Derivatives · Hydrocarbons · Halogen Compounds17M
Q6Polymerisation · Nitrogen Compounds10M
Q7Analytical Techniques · Halogen Compounds10M
Q8Polymerisation · Hydroxy Compounds10M

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