Q.What do you mean by the activity and selectivity of a catalyst?

Step 1. The activity of a catalyst refers to how effectively it speeds up a given reaction — a highly active catalyst lowers the activation energy substantially and increases the rate strongly, while a less active catalyst produces only a modest rate increase for the same reaction. Activity is closely tied to how many active centres the catalyst surface presents and how strongly reactants are adsorbed and activated there.

Step 2. The selectivity of a catalyst, by contrast, refers to its ability to direct a reaction preferentially toward ONE particular product, out of several products that might in principle be possible from the same reactants — a highly selective catalyst gives almost exclusively the desired product, while a less selective one gives a mixture.

Step 3. Zeolite catalysts illustrate selectivity concretely through their shape selectivity: because their acidic (or basic) active sites lie inside narrow pores, only reactant molecules small enough to enter the pore can reach the active site (reactant selectivity), only transition states small enough to fit within the pore can actually form (transition-state selectivity), and only product molecules small enough to diffuse back out actually appear as isolable product (product selectivity) — the pore geometry itself enforces a high degree of selectivity that an open, unconfined catalyst surface could not achieve. …

Define activity as rate-enhancing power and selectivity as product-directing precision, then illustrate select …

Treating activity and selectivity as the same property (a highly active catalyst is not automatically highly selective, and vice versa) instead of recognising t …