Hydrolysis of an ester (e.g., ethyl acetate) in dilute aqueous solution behaves as a first-order reaction even though it is intrinsically second-order. This is because:
AThe activation energy is zero
BEsters are inherently first-order
CWater is in large excess and its concentration changes negligibly during the reaction → 'pseudo-first-order'
DThe rate is independent of ester concentration
Answer & Solution
Correct answer: C. Water is in large excess and its concentration changes negligibly during the reaction → 'pseudo-first-order'
**Pseudo-first-order reaction**: when one reactant (here water) is in such large excess that its concentration is effectively constant, the rate law collapses to first-order. Inversion of cane sugar is another pseudo-first-order example.
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