Question

Inversion of cane sugar in dilute acid is:

• A. bimolecular reaction
• B. pseudo-unimolecular reaction
• C. unimolecular reaction
• D. trimolecular reaction

Answer 1

The correct option is B pseudo-unimolecular reaction

$C_{12}{H}_{22}{O}_{11}+H_{2}O\underset{}{\overset{H^{+}}{\to }}{C}_6{H}_{12}{O}_6+C_6{H}_{12}{O}_6$
Rate $=k\left[C_{12}{H}_{22}{O}_{11}\right]\left[H_{2}O\right]$
When water is in excess, its concentration will be constant.
$\therefore$ Rate $=k^{{}^{\prime }}\left[C_{12}{H}_{22}{O}_{11}\right]$
The reaction is, therefore, pseudo first order or pseudo unimolecular reaction.