Which of the following will not affect the value of equilibrium constant of a reaction?

Options

A. change in the concentration of reactants
B. change in temperature
C. change in pressure
D. addition of catalyst

Answer

To determine which factors do not affect the value of the equilibrium constant (K) for a reaction, we can analyze the factors that influence K.

### Step-by-Step Solution:

1. **Understanding the Equilibrium Constant**:
The equilibrium constant (K) is a value that expresses the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature.

2. **Factors Affecting K**:
- **Temperature**: The equilibrium constant is affected by changes in temperature. For endothermic reactions, increasing the temperature increases K, while for exothermic reactions, increasing the temperature decreases K.
- **Concentration of Reactants and Products**: Changing the concentration of reactants or products does not affect the value of K. It may shift the position of equilibrium, but K remains constant at a given temperature.
- **Pressure**: Changes in pressure (for reactions involving gases) can shift the position of equilibrium, but they do not change the value of K.
- **Catalysts**: The addition of a catalyst speeds up the rate at which equilibrium is reached but does not affect the value of K.

3. **Conclusion**:
Based on the above analysis, the factors that do not affect the value of the equilibrium constant are:
- Change in concentration of reactants and products
- Change in pressure
- Addition of a catalyst

Therefore, the only factor that affects the equilibrium constant is a change in temperature.

### Final Answer:
The factors that will not affect the value of the equilibrium constant are:
- Change in concentration of reactants
- Change in pressure
- Addition of a catalyst