The role of a catalyst is to change: a.) Gibbs energy of reaction b.) Enthalpy of reaction c.) Activation energy of reaction d.) Equilibrium constant.
Hint: If we make a graph of energy vs time of a reaction, we will see a peak most often in the centre of the graph. At this peak point, maximum energy is reached at which most of the reactant is converted to product. After reaching this peak, the graph begins to go down. Catalysts are known to have an influence at this point of the reaction.
Complete step by step solution: A catalyst is a substance which enhances the rate of reaction without itself getting consumed in the reaction. Often, catalysts change the path of the reaction. The maximum amount of work that can be extracted from a closed system is called Gibb's energy of that reaction. The amount of heat absorbed or released by a system (during a chemical reaction), at constant pressure is called the enthalpy of the reaction. The ratio between the amount of reactant and amount of product, for a particular reaction is called as equilibrium constant for that reaction. The minimum amount of extra energy which is required for a reactant molecule to change into a product is called its activation energy. Catalysts cause the molecules to react and make the whole reaction take place faster and efficiently. This effect is achieved by decreasing the activation energy.
So, the correct answer is “Option C”.
Note: Catalysts can be solid, liquid or gaseous in nature. Catalysts are responsible for enhancing the rate of conversion of reactants to product. However, they do not start the reaction. Also, the entire amount of catalyst is recovered at the end of the reaction i.e. no amount is used in the reaction.