Pseudo First Order Reaction - Practice Questions & MCQ

If one reactant is present in large excess a 2^nd order reaction is converted to 1^st order reaction. This is called a pseudo-first-order reaction.

acid catalyzed hydrolysis of ester

$\mathrm{C}_3 \mathrm{H}_6 \mathrm{O}_2+\mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{CH}_3 \mathrm{COOH}+\mathrm{CH}_3 \mathrm{OH}$

This reaction is first order with respect to ester. The 2nd-order reaction with respect to that reactant has been taken in more amounts. For example:

$\begin{aligned} & r=k\left[\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{CH}_3\right]\left[\mathrm{H}_2 \mathrm{O}\right]=k^{\prime}\left[\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{CH}_3\right] \\ & k\left[\mathrm{H}_2 \mathrm{O}\right]=k^{\prime}\end{aligned}$