In the Arrhenius equation , when T → ∞ then R = Ae ° = A when Ea = 0 , k = A and the rate of reaction becomes independent temperature .
Role of Catalyst in a Chemical Reaction
A catalyst is a chemical substance which alters the rate of a reaction WIthout itself undergoing any permanent chemical change .
In the chemical reactions , catalyst provides an alternate pathway or reaction mechanism by reducing the activation energy between reactants and products and hence . lowering the potential energy barrier as shown .
In the presence of catalyst , activation energy decreases and hence .
where , P denotes presence of catalyst and a denotes absence of catalyst .
Theory of Reaction Rates Collision Theory
According to this theory , the reactant molecules are assumed to be hard spheres and the reaction is postulated to occur , when molecules collide with each other .
The number of collisions between the reacting molecules taking place per second per unit volume is known as collision frequency ( ZAB )·