Chemistry - Chemical Kinetics Question with Solution | TestHub

$$\begin{array}{rl}& 3{\mathrm{I}}^{-}+{\mathrm{S}}_2{\mathrm{O}}_8^{2-}\to {\mathrm{I}}_3^{-}+2{\mathrm{SO}}_4^{2-}\\ & \text{ Rate of reaction }=-\frac{1}{3}\frac{\mathrm{d}\left[{\mathrm{I}}^{-}\right]}{\mathrm{dt}}=+\frac{1}{2}\frac{\mathrm{d}\left[{\mathrm{SO}}_4^{2-}\right]}{\mathrm{dt}}\\ & \begin{array}{rl}-\frac{\mathrm{d}\left[{\mathrm{I}}^{-}\right]}{\mathrm{dt}}& =\frac{3}{2}\frac{\mathrm{d}\left[{\mathrm{SO}}_4^{2-}\right]}{\mathrm{dt}}=\frac{3}{2}\times 2.2\times 10^{-2}\\ & =3.3\times 10^{-2}\mathrm{mol}{\mathrm{dm}}^{-3}{\mathrm{s}}^{-1}\end{array}\end{array}$$ [Note: In the question, $\frac{\mathrm{d}\left[{\mathrm{I}}^{-}\right]}{\mathrm{dt}}$ is changed to $-\frac{\mathrm{d}\left[{\mathrm{I}}^{-}\right]}{\mathrm{dt}}$ to apply appropriate textual concepts.]