For the buffer solution containing `NH_(4)OH` and `NH_(4) CI, P^(H)` of the buffer solution can be increased by

Options

A. Adding some more H2O
B. Ading some more `NH_(4),OH `
C. Removing `NH_(4),CI`
D. Both b and c

Answer

To solve the problem regarding how to increase the pH of a buffer solution containing \( \text{NH}_4\text{OH} \) (ammonium hydroxide) and \( \text{NH}_4\text{Cl} \) (ammonium chloride), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Buffer System**:
- The buffer solution consists of a weak base \( \text{NH}_4\text{OH} \) and its conjugate acid \( \text{NH}_4\text{Cl} \).
- This is a basic buffer system.

2. **Identify the Relationship Between pH, pOH, and Concentrations**:
- The pH of a buffer solution can be related to its pOH using the equation:
\[ \text{pH} + \text{pOH} = 14 \]
- The pOH can be expressed using the Henderson-Hasselbalch equation for basic buffers:
\[ \text{pOH} = \text{pK}_b + \log\left(\frac{[\text{Salt}]}{[\text{Base}]}\right) \]
- Therefore, we can express pH as:
\[ \text{pH} = 14 - \text{pK}_b - \log\left(\frac{[\text{Salt}]}{[\text{Base}]}\right) \]

3. **Analyze the Effect of Concentrations on pH**:
- From the equation, we can see that:
- Increasing the concentration of the base (\( \text{NH}_4\text{OH} \)) will increase the pH.
- Decreasing the concentration of the salt (\( \text{NH}_4\text{Cl} \)) will also increase the pH.

4. **Evaluate the Given Options**:
- **Adding more \( \text{H}_2\text{O} \)**: This dilutes both the base and the salt, which does not effectively increase pH.
- **Adding more \( \text{NH}_4\text{OH} \)**: This increases the concentration of the base, thus increasing pH.
- **Removing \( \text{NH}_4\text{Cl} \)**: This decreases the concentration of the salt, thus increasing pH.
- Therefore, both adding more \( \text{NH}_4\text{OH} \) and removing \( \text{NH}_4\text{Cl} \) will increase the pH.

5. **Conclusion**:
- The pH of the buffer solution can be increased by:
- Adding more \( \text{NH}_4\text{OH} \) (base).
- Removing \( \text{NH}_4\text{Cl} \) (salt).
- Hence, the correct answer is both options B and C.

### Final Answer:
The pH of the buffer solution can be increased by adding more \( \text{NH}_4\text{OH} \) and removing \( \text{NH}_4\text{Cl} \) (both B and C).

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