Question

(a) What part of the energy profile of a reaction is affected by a catalyst? (b) What is the difference between a homogeneous and a heterogeneous catalyst?

Short answer

(a) A catalyst affects the transition state of a reaction, lowering the activation energy and allowing reactant molecules to transform into products more easily. (b) Homogeneous catalysts exist in the same phase as the reaction mixture and are usually soluble, while heterogeneous catalysts exist in a different phase, often as a solid in contact with liquid or gaseous reactants. The main difference lies in their interaction levels with reactants, affecting the efficiency and selectivity of the catalytic process.

Step-by-step solution

(a) Identifying the energy profile part affected by a catalyst

A catalyst affects the transition state of a reaction, which is the highest energy point along the reaction pathway. By lowering the activation energy, the catalyst helps the reactant molecules to transform into products more easily.

(b) Defining homogeneous and heterogeneous catalysts

Homogeneous catalysts are those that exist in the same phase as the reaction mixture. They are usually soluble in the reaction medium. On the other hand, heterogeneous catalysts exist in a different phase from the reaction mixture, usually as a solid in contact with the reactants in either liquid or gaseous form. The main difference between the two types of catalysts is the level of interaction between the catalyst and the reactants, which can influence the efficiency and selectivity of the catalytic process.