Which causes the change in the value of equilibrium constant of any equilibria ?

Options

A. Adding of inert gas at constant pressure
B. Increasing the pressure
C. Adding of inert gas at constant volume
D. Decreasing the temperature

Answer

To determine what causes a change in the value of the equilibrium constant for any equilibrium, we can follow these steps:

### Step 1: Understand 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.

### Step 2: Identify Factors Affecting the Equilibrium Constant
The equilibrium constant is influenced by several factors, but it is crucial to note that it is primarily dependent on temperature. Other factors, such as concentration and pressure, can shift the position of equilibrium but do not change the value of K.

### Step 3: Review the Van't Hoff Equation
The Van't Hoff equation relates the change in the equilibrium constant with temperature:
\[ \ln \frac{K_2}{K_1} = \frac{\Delta H}{R} \left( \frac{1}{T_1} - \frac{1}{T_2} \right) \]
Where:
- \( K_1 \) and \( K_2 \) are the equilibrium constants at temperatures \( T_1 \) and \( T_2 \).
- \( \Delta H \) is the change in enthalpy of the reaction.
- \( R \) is the universal gas constant.

### Step 4: Analyze the Options
Given the options:
1. Addition of inert gas at constant pressure
2. Increasing the pressure
3. Adding inert gas at constant volume
4. Decreasing the temperature

From the analysis, we see that:
- The addition of an inert gas at constant pressure or volume does not change the concentrations of reactants or products, hence does not change K.
- Increasing the pressure can shift the equilibrium position but does not change K.
- Decreasing the temperature affects the value of K, as indicated by the Van't Hoff equation.

### Conclusion
The only factor that causes a change in the value of the equilibrium constant is **decreasing the temperature**.

### Final Answer
**Decreasing the temperature causes a change in the value of the equilibrium constant.**

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