Half-life of a reaction (t1/2)

Definition

The half-life of a reaction ($t_{1/2}$) is the time required for the concentration of a reactant to decrease to half of its initial value. It provides insight into the rate at which a reaction proceeds.

5 Must Know Facts For Your Next Test

1. For a first-order reaction, the half-life is constant and does not depend on the initial concentration of the reactant.
2. For a second-order reaction, the half-life is inversely proportional to the initial concentration of the reactant.
3. In zero-order reactions, the half-life is directly proportional to the initial concentration of the reactant.
4. $t_{1/2} = \frac{0.693}{k}$ for first-order reactions, where $k$ is the rate constant.
5. Half-life concepts are crucial in fields such as pharmacokinetics, environmental science, and nuclear chemistry.

Review Questions

Related terms

Rate Constant (k): A proportionality constant that relates the rate of a reaction to the concentrations of reactants.

First-Order Reaction:

A reaction where the rate depends linearly on only one reactant's concentration.

Integrated Rate Law:

An equation that links concentrations of reactants or products with time directly.