Chemistry 9701 · AS & A Level · Reaction kinetics

Reaction kinetics — practice question

A bromoalkane, R-Br, undergoes hydrolysis with aqueous sodium hydroxide.
(a(i))

Write a balanced equation for this reaction.

(a(ii))[2]

What sort of reaction is this?

(b(i))

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

(b(ii))

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

(b(iii))

Use the graphs to calculate the order of reaction with respect to NaOH. Show all your working, and make any construction lines on the graphs clear.

(b(iv))[7]

Write the rate equation for this reaction, and calculate the rate constant. rate $=

(c)[2]

Nitric oxide, NO, and bromine vapour react according to the equation $\text{2NO(g)} + \text{Br}_2\text{(g)} \rightarrow \text{2NOBr(g)}$, with $\Delta H = -23\ \text{kJ mol}^{-1}$. The activation energy for the reaction is $+5.4\ \text{kJ mol}^{-1}$. Use the axes below to sketch a fully labelled reaction pathway diagram for this reaction. Include all the numerical information on your diagram.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: Balanced equation for nucleophilic substitution: $\mathrm{RBr + OH^- \rightarrow ROH + Br^-}$

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