Describe two functions of a catalyst in terms of cause & effect

A catalyst modifies (increase) the rate at which a reaction occurs, by decreasing the activation energy (the energy of the transition state).

The use of a catalyst permits:

- to obtaing higher rates of reaction

- to decrease the temperature needed to get a determined rate of reaction.

In both cases the cause is the lower activation energy, the effects are higher rates of reaction and / or lower temperature.

Higher rates of reaction are important because it is directly related to the productivity.

Lower temperatures are important because the determine the materials of the reactors and the safety devices needed to work.