Question

The role of a catalyst in a reversible reaction is to:
A. Increase the rate of forward reaction
B. Decrease the rate of backward reaction
C. Alter the equilibrium constant of the reaction
D. Allow the equilibrium to be achieved quickly

Answer 1

Hint: A catalyst is a substance that takes part in a chemical reaction, and provides a suitable surface for reactant (catalytic action) resulting in the formation of an unstable intermediate easily. The most interesting part is that the catalyst, a reaction supporter itself, does not interfere in the formation of the product and is released along with the product as it is added to the reactant. Also, it helps to increase the yield of suitable major products and make the chemical reaction more energetic with its catalytic properties.

Complete Step by Step Answer:
A reversible reaction is a reaction that can be reversed or can, say, obtain a reactant from the product by removing the condition applied to the reactant to change it to the product. These reactions at any instant acquire an equilibrium state and further no exchange of energy takes place or the rate of formation of product is equal to the rate of formation of reactant.

A reactant changes to a product and a product changes to a reactant when the reactant and product observe energy greater than the activation energy (energy of transition state). Now, some reactions have large activation energy thus it becomes difficult to provide energy of such an amount, in that case, catalysts are used.

A catalyst is a substance that provides speed to the progress of reaction or can say lowering the activation energy (Ea) required by reactant and product to convert to product and reactant. So we need to provide less energy to reactants to convert to the product and vice versa.

Catalyst does not itself consume and release at the end of reaction but provides a suitable surface to reactant and accelerate the conversion of reactant to a product quickly and the process is known as catalysis. This means it increases the rate of formation of product (affect forward reaction rate) and formation of reactant in a reversible reaction quickly (affect backward reaction rate).
Thus, the correct option is D.

Note: It is important to note that catalyst not only increases the forward reaction rate but also the backward reaction rate equally so options A and B cannot be the suitable choice. Negative catalyst decreases the rate of forward and backward reaction. Activation energy is the minimum amount of energy which we need to provide to reactants to activate it and change the product to show the reaction.