The rate of a reaction is the speed at which reactants are converted into products. It is usually expressed in terms of the change in concentration of a reactant or product per unit time. The rate of a reaction is affected by a number of factors including the concentration of the reactants.
The higher the concentration of the reactants the more collisions there will be between them. This means that there is a greater chance of a reaction taking place. The rate of the reaction will increase as the concentration of the reactants increases.
The following equation shows the relationship between the rate of a reaction and the concentration of a reactant:
rate = k[A]n[B]m
where k is the rate constant [A] and [B] are the concentrations of reactants A and B and n and m are the respective orders of reaction with respect to A and B.
The rate of a reaction can also be affected by the presence of a catalyst. A catalyst is a substance that increases the rate of a reaction by reducing the activation energy. The activation energy is the energy required for a reaction to take place.
A catalyst provides an alternative pathway for the reaction to take place with a lower activation energy. This means that the reaction can take place more easily and at a higher rate.
In general the rate of a reaction will increase as the concentration of the reactants increases. This is because there are more collisions between the reactants which increases the chance of a reaction taking place. The presence of a catalyst can also increase the rate of a reaction by reducing the activation energy.