Which of the following statement is not correct to explain the effect of catalyst on rate of reaction?

Options

A. A catalyst alters the Gibbs' energy of a reaction
B. A catalyst does not change equilibrium constant of a reaction
C. A catalyst reduces the activation energy between reactants and products 7
D. A catalyst provides an alternate reaction mechanism

Answer

To determine which statement is not correct regarding the effect of a catalyst on the rate of reaction, we will analyze each statement one by one.

### 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 does this by lowering the activation energy required for the reaction to occur.

2. **Analyzing the Statements**:
- **Statement 1**: "A catalyst enters the Gibbs energy of a reaction."
- This statement is incorrect. A catalyst does not change the Gibbs free energy (ΔG) of a reaction; it only affects the activation energy.

- **Statement 2**: "A catalyst does not change the equilibrium constant."
- This statement is correct. A catalyst does not affect the position of equilibrium or the equilibrium constant of a reaction; it only speeds up the rate at which equilibrium is reached.

- **Statement 3**: "A catalyst reduces the activation energy between the reactant and the product."
- This statement is correct. One of the primary functions of a catalyst is to lower the activation energy, making it easier for the reaction to occur.

- **Statement 4**: "A catalyst provides a second mechanism."
- This statement is correct. Catalysts can provide an alternative pathway for the reaction, which typically has a lower activation energy.

3. **Identifying the Incorrect Statement**:
- From the analysis, the first statement is the only one that is incorrect regarding the effect of a catalyst on the rate of reaction. Therefore, it is the answer to the question.

### Conclusion:
The statement that is not correct to explain the effect of a catalyst on the rate of reaction is: **"A catalyst enters the Gibbs energy of a reaction."**