The equilibrium constant of an endothermic reaction `………..` with increase of temperature.

Answer

To determine how the equilibrium constant (K) of an endothermic reaction changes with an increase in temperature, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Nature of Endothermic Reactions**:
- An endothermic reaction is one that absorbs heat from the surroundings. This means that the change in enthalpy (ΔH) for the reaction is positive.

2. **Recall the Relationship Between Equilibrium Constant and Temperature**:
- The equilibrium constant (K) for a reaction can be expressed using the van 't Hoff equation:
\[ K = A \cdot e^{-\frac{\Delta H}{RT}} \]
where:
- \( K \) is the equilibrium constant,
- \( A \) is a pre-exponential factor,
- \( \Delta H \) is the change in enthalpy,
- \( R \) is the universal gas constant,
- \( T \) is the temperature in Kelvin.

3. **Analyze the Effect of Temperature on K**:
- Since ΔH is positive for endothermic reactions, as the temperature (T) increases, the term \(-\frac{\Delta H}{RT}\) becomes less negative (i.e., it increases).
- This results in the exponential term \( e^{-\frac{\Delta H}{RT}} \) increasing, which in turn causes the equilibrium constant \( K \) to increase.

4. **Conclusion**:
- Therefore, for an endothermic reaction, the equilibrium constant \( K \) increases with an increase in temperature.

### Final Answer:
The equilibrium constant of an endothermic reaction **increases** with an increase in temperature.