Question:
The reaction $2 \mathrm{~A}+\mathrm{B}_{2} \rightarrow 2 \mathrm{AB}$ is an elementary reaction.
For a certain quantity of reactants, if the volume of the reaction vessel is reduced by a factor of 3 , the rate of the reaction increases by a factor of - (Round off to the Nearest Integer).
Solution:
Reaction : $2 \mathrm{~A}+\mathrm{B}_{2} \longrightarrow 2 \mathrm{AB}$
As the reaction is elementary, the rate of reaction is
$\mathrm{r}=\mathrm{K} \cdot[\mathrm{A}]^{2}\left[\mathrm{~B}_{2}\right]$
on reducing the volume by a factor of 3 , the concentrations of $\mathrm{A}$ and $\mathrm{B}_{2}$ will become 3 times and hence, the rate becomes $3^{2} \times 3=27$ times of initial rate.