Question

What is the effect of a catalyst on the rate of chemical reaction?

Answer 1

Hint: We need to know that a chemical reaction is formed by combining reactants together which further leads to the formation of products. The rate of reaction depends upon the number of reactants participating in a reaction. Catalyst hinders the following in a chemical reaction: activation energy, type of catalyst, temperature and many more.

Complete answer:
A catalyst is any substance which is added to the reaction, to alter the rate of reaction. A catalyst is any substance that increases a reaction rate without being consumed on its own. In other words it’s a substance that increases the rate of a chemical reaction without being changed in identity. 
In the presence of a catalyst, an alternative pathway with lower activation energy is made available. More collisions are successful because less energy is required for success. After the reaction, the catalyst can be recovered after the reaction is over and used again and again. If the reactants and the catalyst are in the same phase the catalysis is said to be homogeneous. With a catalyst, the average kinetic energy of the molecules remains the same but the required energy decreases. Catalysts provide a new reaction pathway in which a lower Activation energy is offered. A catalyst increases the rate of a reaction by lowering the activation energy so that more reactant molecules collide with enough energy to surmount the smaller energy barrier.

Note:
We have to know that the catalyst does not appear in the reaction's net equation and are not consumed during the reaction. Catalysts allow a reaction to proceed via a pathway that has lower activation energy than the un catalyzed reaction. A heterogeneous catalyst exists in a different phase from the reactant molecules.