Question

State two important limitations concerning the behaviour of catalysts in a chemical reaction.

Answer 1

Catalysts are chemical compounds that increase the rate of a reaction by lowering the activation energy required to reach the transition state. Unlike reactants, a catalyst is not consumed as part of the reaction process.

Surface area of the catalyst: Once the catalytic surface is completely saturated with reactant molecules, the reaction cannot proceed until products leave the surface, and some space opens up again for a new reactant molecule to adsorb, or attach. It is for this reason that the adsorption step in a heterogeneously catalyzed reaction is often the rate-limiting step. Catalysts affect reaction kinetics, the equilibrium state remains unaffected.

Toxicity: Catalysts can sometimes be toxic. e.g. transition metals there is a possiblity that it might be toxic when they are released into the environment. Catalysts can also be expensive e.g Gold.