Question1. The net ionic equation for the reaction between sodium thiosulphate and hydrochloric acid is given as $$\mathrm{S}_{2} \mathrm{O}_{3}^{2-}(\mathrm{aq})+2 \mathrm{H}^{+}(\mathrm{aq}) \longrightarrow \mathrm{S}(\mathrm{~s})+\mathrm{SO}_{2}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})$$
To prove that this reaction follows first order kinetics, a student varied the concentration of $\mathrm{S}_{2} \mathrm{O}_{3}{ }^{2-}$ while keeping that of $\mathrm{H}^{+}$constant $(10 \mathrm{~mL}$ of 2 M HCl$)$ and observed the rate of appearance of $\mathrm{S}(\mathrm{s})$ with time. Starting with 50 mL of $0.15 \mathrm{M} \mathrm{S}_{2} \mathrm{O}_{3}{ }^{2-}$, he generated the results shown in table 1 .
Table 1: Results for the clock reaction between $\mathrm{S}_{2} \mathrm{O}_{3}{ }^{2-}$ and $\mathrm{H}^{+}$ \begin{tabular}{|l|l|l|l|l|} \hline Beaker & Vol. $\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3} / \mathrm{mL}$ & Vol. $\mathrm{H}_{2} \mathrm{O} / \mathrm{mL}$ & {$\left[\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}\right] / \mathrm{M}$} & Time/s \\ \hline A & 50.0 & 0.0 & 0.15 & 22.5 \\ \hline B & 40.0 & 10.0 & & 27.3 \\ \hline C & 30.0 & 20.0 & & 35.1 \\ \hline D & 40.0 & 30.0 & & 60.0 \\ \hline E & 10.0 & 40.0 & & 159.1 \\ \hline \end{tabular} a) Copy and complete table 1. b) Plot a graph of $\ln \left[\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}\right]$ (M) against time (s).