Rate Constant
The proportionality constant in a rate law, characteristic of a given reaction at a given temperature.
Formula / equation
k = A e^(−Ea/RT)
Unit
Various
In depth
The rate constant is independent of concentration but rises sharply with temperature and is increased by a catalyst. Its units depend on the overall order, ranging from mol/(L·s) for zero order through s⁻¹ for first order to L/(mol·s) for second order.
Examples in the real world
A first-order rate constant of 0.0231 s⁻¹ corresponds to a half-life of exactly 30 s.