Pseudo First Order

Question

Hydrolysis of ester in large excess water shows pseudo first-order because:

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1. **Theoretical Rate Law**: $Rate = k[Ester][H_2O]$. This is second-order overall.
2. **Concentration Effect**: If the concentration of one reactant ($H_2O$) is present in huge excess (e.g., $55.5$ M), its concentration change during the reaction is negligible.
3. **Simplification**: $[H_2O] \approx 	ext{constant}$. We can define a new rate constant $k' = k[H_2O]$.
4. **Apparent Law**: $Rate = k'[Ester]$.
5. **Definition**: Such reactions, which are not truly first-order but behave as such under specific conditions, are called **pseudo first-order** reactions.

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Pseudo First Order

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More pseudo first order Practice Questions

Hydrolysis of ethyl acetate in presence of excess water follows pseudo first-order kinetics because:

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