Friday, 16 March 2012

Chemistry Form 5 (Chapter 1)



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

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