Question

A negative catalyst will:
A. Lower the activation energy of the reaction.
B. Does not alter the activation energy of the reaction.
C. Provide a new and easy path for the reaction.
D. Increase the activation energy of the reaction.

Answer 1

Hint: Catalyst alters the rate of reaction. The negative catalyst decreases the rate of reaction. A negative catalyst increases the energy difference between transition state and reactant.

Complete answer
That substance that alters the rate of reaction is known as a catalyst.
Based on the effect on the reaction the catalyst are of two types:
1. The catalyst that increases the rate of reaction or activates the reaction is known as a positive catalyst.
2. The catalyst that decreases the rate of reaction or deactivates the reaction is known as a negative catalyst.
When chemical reactions get retard by the presence of any foreign chemical compound, the compound is known as a negative catalyst.
A chemical compound requires some amount of energy to weaken its bonds and break them. So, the compound can form a transition state which leads to the formation of the product.
The energy difference between the transition state and reactant is known as activation energy. Activation energy is the energy which is required to activate the reactant to start the reaction.
A negative catalyst increases the activation energy so now the reactant requires a high amount of energy to start the reaction.
The energy profile diagram showing the effect of a negative catalyst on activation energy is as follows:

Therefore, option (D) Increase the activation energy of the reaction, is correct.

Note:
The positive catalyst decreases the activation energy. Positive catalysts provide a new and easy path for the reaction. The catalyst affects both the reaction, forward as well as backward. The negative catalyst decreases the rate of forward as well as backward direction reactions to the same extent.