Question

Inversion of cane sugar is a pseudo first-order reaction. Give reason.

Answer 1

Pseudo First-order reaction:

• A pseudo-first-order reaction is a second-order or bimolecular reaction that is manipulated to behave as if it were a first-order reaction.
• This reaction occurs when one of the reacting materials is present in large quantities or is kept at a constant concentration in comparison to the other substance.
• Example: Inversion of cane sugar.
• Inversion of cane sugar refers to the process of converting cane sugar to glucose and fructose.
• The reaction proceeds as follows:

$\underset{\mathrm{Sucrose}}{{\mathrm{C}}_{12}{\mathrm{H}}_{22}{\mathrm{O}}_{11}}+\underset{\mathrm{Excess}\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}}\stackrel{{\mathrm{H}}^{+}}{\to }\underset{\mathrm{Glucose}}{{\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6}+\underset{\mathrm{Fructose}}{{\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6}$

• Acid-catalyzed inversion of cane sugar is a pseudo-first-order reaction because water is present in such enormous excess that its concentration remains almost constant throughout the reaction.

Thus, the inversion of cane sugar is a pseudo-first-order reaction.