definition

In chemical kinetics a reaction rate constant k or For a chemical reaction where substance A and B are reacting to produce C, the reaction rate has the form: Reaction: A + B \frac{d[C]}{dt} = k(T)[A]^{m}[B]^{n} k(T) is the reaction rate constant that depends on temperature. [C] is the concentration of substance C in moles per volume of solution assuming the reaction is taking place throughout the volume of the solution (for a reaction taking place at a boundary it would denote something like moles of C per area). The exponents m and n are called orders and depend on the reaction mechanism. They can be determined experimentally. A single-step reaction can also be written as \frac{d[C]}{dt} = Ae^\frac{-E_a}{RT}[A]^m[B]^n Ea is the activation energy and R is the Gas constant. Since at temperature T the molecules have energies according to a Boltzmann distribution, one can expect the proportion of collisions with energy greater than Ea to vary with e-Ea/RT. A is the pre-exponential factor or frequency factor. source: http://en.wikipedia.org/wiki/Rate_constant

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