Question

expain the phenomenon of catalysis?

what are two types if catalysts commonly used ti alter the reaction rate?

Answer 1

Catalysis is the modification of the rate of a chemical reaction (either an increase or a decrease) by addition of a substance which is not consumed during the reaction. That substance is known as catalyst. A catalyst functions by forming bonds with the reacting molecules and by allowing these to react to a product which detaches from the catalyst and leaves it unaltered such that it is available for the next reaction.

The types of catalysts used to alter the reaction rate are:

a) Positive Catalyst - Those catalysts which increase the rate of a chemical reaction are positive catalysts. It increases the rate of reaction by lowering the activation energy barriers. For Example- In Haber's Process Iron Oxide acts as the positive catalyst.

b) Negative Catalyst- Those catalysts which decrease the rate of a chemical reaction are negative catalysts. It decreases the rate of reaction by increasing the activation energy barrier. For Example- Acetanilide acts as the negative catalyst to decrease the rate of decomposition of hydrogen peroxide.