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InterviewSolution
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What do you mean by activity and selectivity of catalysts ? |
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Answer» Solution :Activity: Ability of a catalyst to accelerate chemical reactions is KNOWN as its activity. For EXAMPLE, Pt catalyses the combination of `H_2` and `O_2` to form water. It has been found that for hydrogenation reactions, the catalytic activity increases from Group 5 to Group 11 metals with maximum activity being shown by Group 7-9 ELEMENTS of the periodic table. SELECTIVITY: The ability of a catalyst to direct a reaction to YIELD a particular product is called its selectivity. Combination of CO and `H_2` yields different products with different catalysts as given below: ` CO(g) + 3H_2(g) overset(Ni) to CH_4(g) + H_2O (g)` `CO(g) + H_2(g) overset(Cu)to HCHO (g)` `CO(g) + H_2(g) overset(Cu|ZnO-Cr_2O_3) to CH_3OH(g)` . |
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