First-order kinetics

Definition
noun
An order of chemical reaction in which the rate of the reaction depends on the concentration of only one reactant, and is proportional to the amount of the reactant.
Supplement
It may be represented by the equation, rate = kA, where k is the reaction rate constant, and A is the concentration of the reactant.
An example of a reaction in a first-order is the decomposition of N₂o₅:

N₂o₅ → 2NO₂ + ½ O₂
because the rate of reaction depends on the concentration of N₂o₅ raised to the first power.

Compare: second-order kinetics

See also: chemical kinetics, reactant, reaction rate constant, chemical reaction.