The role of a catalyst is to change……….

Options

A. Gibbs energy of reaction
B. enthalpy of reaction
C. activation energy of reaction
D. equilibrium constant

Explanation

### Step-by-Step Solution:

1. **Understanding the Role of a Catalyst**:
- A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It achieves this by providing an alternative reaction pathway.

2. **Activation Energy**:
- Activation energy (Ea) is the minimum energy required for a chemical reaction to occur. It is a barrier that reactants must overcome to be converted into products.

3. **Effect of a Catalyst on Activation Energy**:
- A catalyst lowers the activation energy of a reaction. This means that the energy barrier for the reaction is reduced, allowing more reactant molecules to have sufficient energy to react.

4. **Energy Profile Diagram**:
- In an energy profile diagram, the y-axis represents potential energy, and the x-axis represents the reaction coordinate (progress of the reaction).
- Without a catalyst, the energy profile shows a higher peak (higher activation energy) that the reactants must reach to form products.
- With a catalyst, the energy profile shows a lower peak (lower activation energy), indicating that the reaction can proceed more easily.

5. **Conclusion**:
- The primary role of a catalyst is to change the activation energy of a reaction, thereby increasing the rate of the reaction without undergoing any permanent change itself.

### Final Answer:
The role of a catalyst is to change the activation energy of a reaction.

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