What is collision theory?

How does it relate to factors that affect reaction rate?

Collision theory is a theory proposed

independently by [1] Max Trautz in 1916 and

William Lewis in 1918, that qualitatively explains

how chemical reactions occur and why reaction

rates differ for different reactions. [2] The

collision theory states that when suitable

particles of the reactant hit each other, only a

certain percentage of the collisions cause any

noticeable or significant chemical change; these

successful changes are called successful

collisions. The successful collisions have enough

energy, also known as activation energy, at the

moment of impact to break the preexisting

bonds and form all new bonds. This results in the

products of the reaction. Increasing the

concentration of the reactant particles or

raising the temperature, thus bringing about

more collisions and therefore many more

successful collisions, increases the rate of

reaction.

When a catalyst is involved in the collision

between the reactant molecules, less energy is

required for the chemical change to take place,

and hence more collisions have sufficient energy

for reaction to occur. The reaction rate

therefore increases.

Collision theory is closely related to chemical

kinetics.