When a catalyst increases the rate of chemical reaction the rate constant :-

Options

A. Increases
B. Decreases
C. Remains constant
D. Becomes infinite

Answer

To solve the question "When a catalyst increases the rate of chemical reaction, the rate constant:", we can follow these steps:

### Step 1: Understand 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 lowering the activation energy required for the reaction to occur.

**Hint:** Remember that catalysts do not change the overall energy of the reaction; they only provide an alternative pathway with lower activation energy.

### Step 2: Define Rate Constant
The rate constant (k) is a proportionality constant that relates the rate of a reaction to the concentrations of the reactants. The rate law for a reaction can be expressed as:
\[ \text{Rate} = k \cdot [\text{Reactants}]^n \]
where \( n \) is the order of the reaction.

**Hint:** The rate constant is specific to a given reaction at a particular temperature.

### Step 3: Relate Activation Energy and Rate Constant
According to the Arrhenius equation:
\[ k = A \cdot e^{-\frac{E_a}{RT}} \]
where:
- \( k \) = rate constant
- \( A \) = pre-exponential factor
- \( E_a \) = activation energy
- \( R \) = gas constant
- \( T \) = temperature

From this equation, we can see that the rate constant \( k \) is inversely proportional to the activation energy \( E_a \).

**Hint:** A lower activation energy means that more molecules have enough energy to react, which increases the rate constant.

### Step 4: Analyze the Effect of a Catalyst
When a catalyst is introduced, it lowers the activation energy \( E_a \). As a result, according to the Arrhenius equation, the rate constant \( k \) increases.

**Hint:** Focus on how the catalyst affects the energy barrier for the reaction.

### Step 5: Conclusion
Since the catalyst increases the rate of the reaction by decreasing the activation energy, the rate constant \( k \) must also increase.

**Final Answer:** The rate constant increases when a catalyst increases the rate of a chemical reaction.

**Correct Option:** Increases (Option 1)