question_answer 28)

What do you mean by activity and selectivity of catalyst?

Answer:

Activity. It is the ability of a catalyst to catalyse a reaction (i.e., to increase the rate of reaction) e.g., H2 and do not react to form water even if kept for indefinite period but in the presence of platinum catalyst, the reaction takes place with explosion. (a) Selectivity. By selectivity we mean the ability of a catalyst to catalyse a particular reaction and not the other reactions. e.g., Depending upon the catalyst used, CO and H2 react to form different products. CO(g) + 3H2(g)  CH4 (g) + H­2O (g) CO(g) + 2H2 (g)  CH­3OH (g) CO (g) + H2 (g) HCHO(g)