Question

A first order reaction has a rate constant of 1.00s−1. What is the half life of the reaction?

Answer 1

For a first order reaction only, the half life is a constant and is proportional to the inverse of the rate constant.

From the integrated rate law, we get [A]=[A]e−kt

Half-life is the time taken for the concentration of a reactant to drop to half its original value [A]=[A0]2

Substituting and taking lograthms on both sides, it can be shown that t1/2=ln2k=0.693k

Given that k=1/s,→t1/2=0.693s