Chemistry 9701 · AS & A Level · Reaction kinetics

Reaction kinetics — practice question

In the following acid-catalysed hydrolysis, ethyl ethanoate reacts slowly with water: $\text{CH}_3\text{CO}_2\text{CH}_2\text{CH}_3 + \text{H}_2\text{O} \xrightarrow{\text{H}^+} \text{CH}_3\text{CO}_2\text{H} + \text{CH}_3\text{CH}_2\text{OH}$. The concentration of ethyl ethanoate was measured at regular intervals while the reaction proceeded. Two experiments were done with different HCl concentrations. The graph below gives the results for an experiment with $[\text{HCl}] = 0.1\,\text{mol dm}^{-3}$.
(a(i))

For the experiment performed with $[\text{HCl}] = 0.2\,\text{mol dm}^{-3}$, the results below were recorded. Plot these points on the axes above, then draw a best-fit line.

(a(ii))

Use either graph to demonstrate that the reaction is first order with respect to $\text{CH}_3\text{CO}_2\text{CH}_2\text{CH}_3$. Present all your working, and make any construction lines on the graphs clearly visible.

(a(iii))

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

(a(iv))[7]

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

(b(i))

Why can the order of reaction with respect to water not be determined in this experiment?

(b(ii))[2]

Although $[\text{CH}_3\text{CO}_2\text{CH}_2\text{CH}_3]$ falls during each experiment, $[\text{HCl}]$ stays equal to its starting value. Why is this?

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