Half-life Conceptual
Which reaction order has half-life independent of initial concentration?
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About This Question
- Subject
- chemistry
- Chapter
- chemical kinetics
- Topic
- half-life conceptual
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
First order
- General Expression: t1/2∝[A]01−n, where n is the reaction order.
- Zero Order (n=0): t1/2∝[A]0. Half-life increases as concentration increases.
- First Order (n=1): t1/2∝[A]00. This means t1/2 is a constant (0.693/k), independent of how much reactant you start with.
- Second Order (n=2): t1/2∝[A]0−1. Half-life is inversely proportional to concentration.
- Summary: First-order kinetics (like radioactive decay) are unique because they take the same time to reduce concentration from 100→50 as from 50→25.
This medium difficulty chemistry question is from the chapter chemical kinetics, covering the topic of half-life conceptual. It appeared in the 2025 exam.
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