Question

Which is a characteristic of a catalyst?
(a)- It changes the equilibrium point
(b)- It initiates the reaction
(c)- It alters the rate of reaction
(d)- It increases the average kinetic energy of the molecule

Answer 1

Catalyst is a compound that is very important for a chemical reaction to occur. If acts on both types of reaction, i.e., reversible and non-reversible so the equilibrium remains the same for a reaction.

Complete step by step answer:
We can define the term catalyst as a substance that has the ability to speed up a chemical reaction without itself undergoing any in its mass and composition at the end of the chemical reaction and this phenomenon is known as catalysis.
There are some properties of the catalyst and these are given below:
(i)- Even a small amount of the catalyst is sufficient to bring about a large change in the rate of reaction.
(ii)- A catalyst is not able to initiate the reaction but it can accelerate the rate of reaction. In other words, it catalyzes a spontaneous reaction and does not catalyze a non-spontaneous reaction.
(iii)- It does not alter the free energy change of the reaction and can be represented as $\Delta G$.
(iv)- It does not alter the enthalpy change of the reaction and can be represented as $\Delta H$.
(v)- A catalyst takes place in the reaction but is regenerated without any chemical change at the end of the reaction.
(vi)- For a reversible reaction, it accelerates the speed of forward reaction as well as that of backward reaction to the same extent. Hence, it does not disturb the equilibrium, i.e., does not change the equilibrium constant of the reaction but simply helps to attain that equilibrium quickly.

Therefore the correct answer is an option (c)- It alters the rate of reaction.

Note: Some examples of catalysts are: in Haber's process iron is used as catalyst, in the polymerization of ethene Ziegler-Natta catalyst, in Fischer-Tropsch process iron or cobalt is used as a catalyst.