Chemistry 9701 · AS & A Level · States of matter

States of matter — practice question

When dissolved in water, 2-chloro-2-methylpropane, $(\text{CH}_3)_3\text{CCl}$, reacts with sodium hydroxide, NaOH. The reaction is a nucleophilic substitution reaction. $(\text{CH}_3)_3\text{CCl}(aq) + \text{NaOH}(aq) \rightarrow (\text{CH}_3)_3\text{COH}(aq) + \text{NaCl}(aq)$
(a)[3]

Draw the mechanism for this reaction. Include every required curly arrow, lone pair and relevant dipole.

(b)

The graph below presents the results of the experiment.

(b(i))[1]

What does the term half-life of a reaction mean?

(b(ii))[1]

Calculate the half-life for this reaction. Present all your working and make any construction lines on the graph clearly visible.

(b(iii))[1]

What effect would doubling the initial concentration of $(\text{CH}_3)_3\text{CCl}$ have on the half-life of this reaction?

(c(i))[2]

Using the graph in part (b), determine the rate of reaction at $80\,\text{s}$. Show all your working.

(c(ii))[1]

Calculate the value of the rate constant, $k$, for this reaction, and state its units.

(i)[1]

What does the term half-life of a reaction mean?

(ii)[1]

Calculate the half-life for this reaction. Present all your working and make any construction lines on the graph clearly visible.

(iii)[1]

What effect would doubling the initial concentration of $[(\text{CH}_3)_3\text{CCl}]$ have on the half-life of this reaction?

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: Dipole placed on the C-Cl bond

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