The pka of acetic acid and pkb of ammonium hydroxide are 4.76 and 4.75 respectively. Calculate the pH of ammonium acetate solution.

Answer

To calculate the pH of an ammonium acetate solution using the given pKa of acetic acid and pKb of ammonium hydroxide, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Values:**
- pKa of acetic acid (CH₃COOH) = 4.76
- pKb of ammonium hydroxide (NH₄OH) = 4.75

2. **Use the Formula for pH of a Salt Solution:**
The pH of a solution of a salt formed from a weak acid and a weak base can be calculated using the formula:
\[ \text{pH} = 7 + \frac{1}{2} (\text{pKa} - \text{pKb}) \]

3. **Substitute the Values into the Formula:**
\[ \text{pH} = 7 + \frac{1}{2} (4.76 - 4.75) \]

4. **Calculate the Difference:**
\[ 4.76 - 4.75 = 0.01 \]

5. **Divide by 2:**
\[ \frac{0.01}{2} = 0.005 \]

6. **Add to 7:**
\[ \text{pH} = 7 + 0.005 = 7.005 \]

### Final Answer:
The pH of the ammonium acetate solution is **7.005**.

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