Question

Reaction $3Cl{O}^{-}⟶Cl{O}_2^{-}+2{Cl}^{-}$
(i) $Cl{O}^{-}+Cl{O}^{-}\underset{}{\overset{K_1}{\to }}Cl{O}_2^{-}+{Cl}^{-}$ (Slow step)
(ii) $Cl{O}_2^{-}+Cl{O}^{-}\underset{}{\overset{K_2}{\to }}Cl{O}_3^{-}+{Cl}^{-}$ (Fast step)
then the rate of given reaction = ______

• A. $K_1{\left[Cl{O}^{-}\right]}^2$
• B. $K_1{\left[Cl{O}^{-}\right]}^{}$
• C. $K_2{\left[Cl{O}_2^{-}\right]}^{}\left[Cl{O}^{-}\right]$
• D. $K_2{\left[Cl{O}^{-}\right]}^3$

Answer 1

The correct option is A $K_1{\left[Cl{O}^{-}\right]}^2$

Rate of reaction depends on slow step and its rate constant.Here slow step is $Cl{O}^{-}+Cl{O}^{-}\to Cl{O}_2^{-}+C{l}^{-}$.

Rate is given by $Rate=K\left[Reactants\right]$ .

So, in this case, we have $Cl{O}^{-}$ as reactants and rate is given by the product of their concentrations and rate constant of that slow step.

Hence rate of this given reaction is $Rate=K_1\left[Cl{O}^{-}\right]\left[Cl{O}^{-}\right]=K_1[Cl{O}^{-}{]}^2$.