In a first-order reaction, if the half-life is constant, what can be said about

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Question: In a first-order reaction, if the half-life is constant, what can be said about the rate constant? (2023)

Options:

Correct Answer: It remains constant

Exam Year: 2023

Solution:

In a first-order reaction, the half-life is constant, which indicates that the rate constant remains constant.

In a first-order reaction, if the half-life is constant, what can be said about the rate constant? (2023)

In a first-order reaction, if the half-life is constant, what can be said about the rate constant? (2023)

Step 1: Understand what a first-order reaction is. In a first-order reaction, the rate of the reaction depends on the concentration of one reactant.
Step 2: Learn about half-life. The half-life is the time it takes for half of the reactant to be consumed.
Step 3: Note that in a first-order reaction, the half-life does not change as the reaction proceeds. It remains constant.
Step 4: Recognize that if the half-life is constant, it means that the rate at which the reaction occurs (the rate constant) does not change.
Step 5: Conclude that in a first-order reaction with a constant half-life, the rate constant must also be constant.

First-Order Reactions – In first-order reactions, the rate of reaction is directly proportional to the concentration of one reactant, and the half-life is independent of the initial concentration.
Half-Life – The half-life of a reaction is the time required for the concentration of a reactant to decrease to half its initial value, which remains constant for first-order reactions.
Rate Constant – The rate constant (k) is a proportionality factor in the rate equation, and for first-order reactions, it is constant and directly related to the half-life.