Chemistry 5070 · O Level · Rate of reaction

Rate of reaction — practice question

Propanone, CH$_3$COCH$_3$, reacts with iodine, I$_2$, to make colourless products. CH$_3$COCH$_3$ + I$_2$ $\rightarrow$ CH$_3$COCH$_2$I + HI Hydrochloric acid is the catalyst for this reaction. The table shows how the relative rate of reaction changes when different concentrations of propanone, iodine and hydrochloric acid are used.
(a)[3]

Describe the effect on the relative rate of reaction when the concentration of each substance is increased. propanone [BLANK] iodine [BLANK] hydrochloric acid [BLANK]

(b)[2]

The temperature of this reaction is increased. Explain why this increases the rate, using kinetic particle theory.

(c)[1]

Iodine exists as more than one isotope. What do isotopes mean?

(d)[1]

Astatine, At, is a halogen. When aqueous iodine reacts with aqueous astatide ions, At$^-$, astatine is formed. Write the ionic equation for this reaction.

(e)[1]

Aqueous hydrogen iodide reduces hydrogen peroxide to water. $\text{H}_2\text{O}_2(aq) + 2\text{H}^+(aq) + 2\text{I}^-(aq) \rightarrow 2\text{H}_2\text{O}(l) + \text{I}_2(aq)$ Explain how iodide ions function as a reducing agent in this reaction.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Raising the propanone concentration increases the rate / doubling it doubles the rate” …

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