Question

A catalysts can affect reversible reaction by
A. Changing equilibrium
B. Slowing forward reaction
C. Attaining equilibrium in both direction
D. None of these

Answer 1

Hint: A catalyst plays a very important role in chemical reactions. It makes a reaction faster by reducing the reaction’s activation energy. Activation energy means the minimum energy needed by the reactant molecules to undergo a chemical reaction to form products.

Complete Step by Step Answer:
Let's understand what happens with the addition of a catalyst to a system. The role of the catalyst is to speed up both the forward and the backward reactions. Thus, it helps to achieve the equilibrium state early. But the concentration at equilibrium is not changed, that is, the equilibrium constant is not changed.
Let’s discuss how a catalyst speeds up reactions. A catalyst fastens both the forward and backward reactions. So, the equilibrium state is achieved early. But there is no change in concentration in the equilibrium. That means, there is no change in the equilibrium constant.
Let's discuss all the options one by one.
Option A says a catalyst affects reversible reaction by change of equilibrium. It is not true because catalysts only help to achieve an equilibrium state early. So, A is wrong.
Option B says the forward reaction slows down and causes a reversible reaction. It is not true because both backward and forward reaction increases with the addition of a catalyst. So, the B option is also not true.
Option C says reversible reaction happens because of the attainment of equilibrium in both directions. It is true because the equilibrium state is achieved early in both directions.
Therefore, option C is right.

Note: It is to be noted that a catalyst is never consumed in a chemical reaction although it fastens a reaction. But it acts in a repeated manner to fasten a reaction. So, fewer catalysts is sufficient for a reaction.