Chemistry Form 5: Chapter 1 - Catalyst Affects the Rate of Reaction

Catalyst is a chemical substance that change the rate of chemical reaction.

Characteristics of catalyst:

• Catalyst remains chemically unchanged during reaction. Its chemical composition still the same before and after reaction.
• Catalyst only change the rate of reaction.
• Catalyst does not change the quantity of the product formed.
• Catalyst is specific in its action.
• Only a small amount of catalyst is needed to achieve a big increase in rate of reaction.

 How catalyst increase the rate of reaction:

• When a positive catalyst is used in a chemical reaction, it enables the reaction to occur through an alternative path which requires lower activation energy.
• As a result, more colliding particles are able to overcome the lower activation energy.
• This causes the frequency of effective collision to increase.
• Hence, the rate of reaction increases.

Decomposition of hydrogen peroxide by catalyst of manganese (IV) oxide