Browse Questions

# For the reaction $S_2O_3^{2-} (aq) + 2H_3O^+ (aq) \rightleftharpoons S (s) + H_2SO_3 (aq) + H_2O(l)$; Rate = $k [H_3O^+][S_2O_3^{2-}]$. Reaction is fastest in

(a) 0.1 M $CH_3COOH$

(b) 0.1 M $H_2SO_4$

(c) 0.1 M HCl

(d) 0.1 M NaOH

Answer: 0.1 M $H_2SO_4$

The reaction will be fastest when $[H_3O^+]$ is maximum.

$[H^+]$ from 0.1 M $CH_3COOH$ < 0.1 M
$[H^+]$ from 0.1 M $H_2SO_4$ = 0.2 M
$[H^+]$ from 0.1 M $HCl$ = 0.1 M
$[H^+]$ from 0.1 M $NaOH$ $10^{-13}$ M