The chemical reactions can be carried out at a faster rate by increasing the temperature , but this is not possible in case of all reaction, Moreover, the reactions can be carried out of a lower temperature by using a catalyst . Since the process takes place at a lower place at a lower temperature, the cost of production gets reduced. A catalyst increases the rate of reaction by providing an alternative path for the reaction. This alternative path is associated with lower activation energy compared to the uncatalysed reaction, which is evident from the following graph.
In most of the reactions catalysts increases the rate of reactions. These types of catalysts are called positive catalysts.
Example : `2SO_(2) + O_(2) overset(NO)to 2SO_(3)`
There are few reactions in which catalysts slow down the rate of reactions. These type of catalysts are called negative catalysts.
Example: Decomposition of hydrogen peroxide can be slowed down if some substances like glycerine, urea, acetanilide, sodium pyrophosphate etc. are added to `H_(2)O_(2)`.
