For a reaction between A and B, the collision frequency (Z) is the number of collisions between A and B occurring in the container per unit volume per unit time.
SI unit of Z is number of collision , where is Avogadro constant.
- is the number density of A in the gas (unit ),
- is the number density of B in the gas (unit ),
- is the reaction cross section (unit ), the area when two molecules collide with each other, simplified to , where the radius of A and the radius of B.
- is the Boltzmann's constant unit ,
- is the temperature (unit ),
- is the reduced mass of the reactants A and B, (unit )