5 - Kinetics - AQA A-level Chemistry

Rate of reaction

Change in concentration of a reactant or product per unit time

Activation energy (Ea)

The minimum energy required for a reaction to occur

Collision theory

Reactions occur when particles collide with sufficient energy and correct orientation

Successful collision

A collision that results in a reaction due to sufficient energy and correct orientation

Frequency of collisions

How often particles collide per unit time

Temperature

A measure of the average kinetic energy of particles

Catalyst

A substance that increases reaction rate by providing an alternative pathway with lower activation energy and is not used up

Homogeneous catalyst

A catalyst in the same physical state as the reactants.

Heterogeneous catalyst

A catalyst in the different physical state as the reactants.

Boltzmann distribution

A curve showing the distribution of the particles energies in a sample

Maxell-Boltzmann curve

A graph showing the spread of molecular energies at a given temperature

What does the top of the Maxwell-Boltzmann curve show?

Most probable energy

Where on a Maxwell-Boltzmann curve indicates the mean energy of the particles?

Slightly right of the top of the curve due to the asymptote of levels of highest particles

Surface area

The total exposed area of a solid reactant that can collide with particles

Initial rate

The rate measured at the start of a reaction