sed to $400.K$ from $298K?$

$O{I}^{-}(aq)+C{l}^{-}(aq)I{C}^{-}(aq)+OC{l}^{-}(aq)$ lowing $C{l}^{-}(aq)$ occurring in aqueous solution, the following mechanism has been proposed:

$OC{l}^{-}(aq)+H_{2}O(l){}^{k_1}{?}^{k_{-1}}$HOCl$(aq)+O{H}^{-}(aq)$

$I^{-}(aq)+$HOCl$(aq)k_2$HOI$(aq)+C{l}^{-}(aq)$

HOI$(aq)+O{H}^{-}(aq)k_3{H}_{2}O(1)+O{I}^{-}(aq)$

a$.$ Derive the rate law expression for this reaction based on this mechanism. $($Hint: $O{H}^{-}$should appear in the rate law.$)$

b$.$ The initial rate of reaction was studied as a function of concentration by Chia and Connick $[$J$.$ Physical Chemistry $63(1959)$: $1518],$ and the following data were obtained: