Question

Efficiency of the catalyst depends on its:

• A. molecular weight
• B. number of free valencies
• C. physical state
• D. amount used

Answer 1

Answer: (B)

number of free valencies

The distribution of free bonds on the catalyst surface is not uniform. These are crowded at the 'peaks', cracks' and corners of the catalyst. The catalytic activity due to adsorption of reacting molecules is maximum at these spots. These are, therefore, referred to as the active centers. The active centers i.e free valencies increase the rate of reaction not only by increasing the concentration of the reactants, but they also activate the molecule adsorbed at two such centers by stretching it.