Question

What are promoters and inhibitors?

Answer 1

In chemistry, we use promoters and inhibitors for the functioning of the catalyst which is used to speed up the reaction. In some reactions, we use promoters and inhibitors with a catalyst which either increases the functioning of the catalyst or decreases the functioning of the catalyst.

Complete step-by-step answer: There are many reactions in which the rate of the reaction is very slow, but for increasing its speed or the rate of reaction we use a catalyst in the reaction. So, catalysts are those compounds that are used in the reaction which enhances the rate of the reaction but it itself doesn't undergo any changes.
There are some compounds that are used with the catalyst which either increases the functioning of the catalyst or decreases the functioning of the catalyst, these are known as promoters and inhibitors.
As the name suggests, promoters are the compounds that increase the functioning of the catalyst, this is done by the fact that the promoters increase the roughness of the surface which increases the free valances and increases the rate. An example of the promoter is molybdenum as a promoter for iron catalyst in the Haber's process.
Inhibitors are those compounds that decrease the functioning of the catalyst because the inhibitors get absorbed on the surface of the reactant which decreases free valances and decreases the rate. An example of inhibitors is arsenic, carbon monoxide ($CO$), etc.

Note: We can also classify the catalyst into two: positive and negative catalyst. Positive are those which enhance the rate of the reaction while negative are those which decrease the rate of the reaction.