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Pseudo First Order

Mediumchemistry

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

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About This Question

Subject
chemistry
Chapter
chemical kinetics
Topic
pseudo first order
Difficulty
Medium
Year
2025
Tags
Pseudo First OrderHydrolysisEster Hydrolysis

Solution

Correct Answer:

Water concentration remains constant

Reaction:

  • The experimental rate law is \text{Rate} = k [CH_3COOC_2H_5] [H_2_O].
  • When water is in large excess, its concentration does not change significantly during the reaction.
  • Thus, can be considered constant and absorbed into the rate constant: , where .
  • Such a reaction, which is higher order but behaves as first order, is called a Pseudo First-Order Reaction.

This medium difficulty chemistry question is from the chapter chemical kinetics, covering the topic of pseudo first order. It appeared in the 2025 exam.

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