Presence of catalyst will ...... the equilibrium constant.

Answer

To answer the question "Presence of catalyst will ...... the equilibrium constant," we can break down the reasoning step by step:

### Step-by-Step Solution:

1. **Understanding Catalysts**: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It works by lowering the activation energy required for the reaction to proceed.

2. **Effect on Reaction Rates**: When a catalyst is added to a reaction, it accelerates both the forward and reverse reactions equally. This means that the rates of the reactions are increased, allowing the system to reach equilibrium faster.

3. **Equilibrium Constant Definition**: The equilibrium constant (K) for a reaction at equilibrium is defined as the ratio of the concentrations of the products to the concentrations of the reactants, each raised to the power of their coefficients in the balanced equation.

4. **Equilibrium Constant and Activation Energy**: The equilibrium constant is related to the Gibbs free energy change (ΔG) of the reaction, which is a thermodynamic property. The relationship is given by the equation:
\[ \Delta G = -RT \ln K \]
where R is the universal gas constant and T is the temperature in Kelvin.

5. **Catalysts and Thermodynamics**: While a catalyst lowers the activation energy for both the forward and reverse reactions, it does not change the overall energy difference between the reactants and products (ΔH). Therefore, the ΔG remains unchanged.

6. **Conclusion**: Since the equilibrium constant (K) is derived from the Gibbs free energy change (ΔG), and ΔG is unaffected by the presence of a catalyst, the equilibrium constant (K) also remains unchanged.

### Final Answer:
The presence of a catalyst will **not change** the equilibrium constant.

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