A first-order reaction is a chemical reaction in which the rate of reaction is directly proportional to the concentration of a single reactant. Mathematically, the rate equation for a first-order reaction is expressed as −d[A]/dt=k[A], where [A] is the concentration of the reactant, t is time, k is the rate constant, and the negative sign indicates the decrease in concentration over time. In a first-order reaction, the reaction rate decreases exponentially as the concentration of the reactant diminishes. This type of reaction is common in radioactive decay and certain chemical processes. The concept of first-order reactions is fundamental in kinetics, providing insights into reaction mechanisms and reaction rate analysis.
