Question

Which among the following reactions is an example of pseudo first order reaction ?

• A. Inversion of cane sugar
• B. Decomposition of $H_2{O}_2$
• C. Conversion of cyclopropane to propene
• D. Decomposition of $N_2{O}_5$

Answer 1

The correct option is A Inversion of cane sugar

Inversion of cane sugar is an example of pseudo first-order reaction as water is present in large excess. Hence, $\left[H_{2}O\right]$ remains constant and does not appear in the rate law expression.

$C_{12}{H}_{22}{O}_{11}+H_{2}O\to C_6{H}_{12}{O}_6\text{(glucose )}+C_6{H}_{12}{O}_6\text{(fructose )}$

Another example is the hydrolysis of methyl acetate.

The following are the examples of first-order reaction.

(B) Decomposition of $H_2{O}_2$

(C) Conversion of cyclopropane to propene

(D) Decomposition of $N_2{O}_5$