Taking two examples of heterogeneously catalyzed reactions, explain how a heterogeneous catalyst helps in the reaction.

Explanation

Solid catalyst are used in a number of gaseoue reactions. Such catalytic reactions are called heterogeous reactions. Examples of hetergeous catalysis are follows.
a. Manufacture of ammonia `N_(2)` and `H_(2)` by Haber's process in the presence of catalyst.
`N_(2)(g)+3H_(2)(g)overset(Fe(s))(rarr)2NH_(3)(g)`
`V_(2)O_(5)` catalyst is used in the manufacture of `H_(2)SO_(4)` by constact process.
`2SO_(2)(g)+O_(2)(g)overset(V_(2)o_(5)(s))(rarr)2SO_(3)(g)`
Solid catalyst helps in the following ways:
i. Simultanceous adsorption of reactants increases with concentration at the surface of the reaction rate.
ii. Adsorption of reactant molecules makes the attack of other molecules on it easier.
iii. Some adsorbed molecules dissociate into atoms which are very reactive.
iv. The heat of adsorption released provides activation energy for the reaction.