Which of the following do not change the value of K for a reaction?

Options

A. Addition of catalyst
B. Increase in temperature
C. Increase in pressure
D. Removal of one of the products

Answer

To determine which of the following options does not change the value of the equilibrium constant (K) for a reaction, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding the Equilibrium Constant (K)**:
- 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. It is important to note that K is only affected by changes in temperature.

2. **Option 1: Addition of Catalyst**:
- A catalyst speeds up the rate of both the forward and reverse reactions equally. It does not change the position of equilibrium or the concentrations of reactants and products at equilibrium. Therefore, the addition of a catalyst does not change the value of K.
- **Conclusion**: This option does not change K.

3. **Option 2: Increase in Temperature**:
- The value of K is dependent on temperature. For an exothermic reaction, increasing the temperature will shift the equilibrium to favor the reactants, thus decreasing K. For an endothermic reaction, increasing the temperature will favor the products, thus increasing K.
- **Conclusion**: This option changes K.

4. **Option 3: Increase in Pressure**:
- Increasing pressure affects the position of equilibrium, particularly in reactions involving gases. According to Le Chatelier's principle, increasing pressure will shift the equilibrium towards the side with fewer moles of gas. This change in position of equilibrium can alter the concentrations of reactants and products, thus changing K.
- **Conclusion**: This option changes K.

5. **Option 4: Removal of One of the Products**:
- Removing a product will shift the equilibrium to the right to produce more products, according to Le Chatelier's principle. This change in concentration will also affect the value of K.
- **Conclusion**: This option changes K.

### Final Answer:
The only option that does not change the value of K for a reaction is **Option 1: Addition of Catalyst**.

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