Kinetics & Equilibrium
What You’ll Learn
The half-life of a first-order reaction is the time required for the reactant concentration to decrease to half of its initial value.
The half-life is independent of the initial reactant concentration and is given by the equation t1/2 = 0.693/k, where k is the rate constant.
After one half-life, 50% of the reactant remains; after two half-lives, 25% remains; and after ten half-lives, less than 0.1% of the original reactant remains. The concept of half-life is important for understanding the kinetics of first-order reactions.