How many grams of solid sodium nitrite should be added to 2.00 L of 0.117 M nitrous acid solution to prepare a buffer with a pH of 4.250? (K₂ for nitrous acid = 4.50E-4) g sodium nitrite

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**Buffer Solution Preparation Calculation**

**Problem Statement:**

How many grams of solid sodium nitrite should be added to 2.00 L of 0.117 M nitrous acid solution to prepare a buffer with a pH of 4.250? ( \( K_a \) for nitrous acid = \( 4.50 \times 10^{-4} \) )

**Solution:**

To solve this problem, we will use the Henderson-Hasselbalch equation for buffer solutions:

\[ \text{pH} = \text{p}K_a + \log \left( \frac{[\text{A}^-]}{[\text{HA}]} \right) \]

Where:
- \( \text{pH} \) is the desired pH of the buffer solution.
- \( \text{p}K_a \) is the negative logarithm of the acid dissociation constant (\( K_a \)).
- \([\text{A}^-]\) is the concentration of the conjugate base.
- \([\text{HA}]\) is the concentration of the weak acid.

1. **Calculate \( \text{p}K_a \):**

\[ \text{p}K_a = -\log ( 4.50 \times 10^{-4} ) \]

2. **Set up the Henderson-Hasselbalch equation and solve for \([\text{A}^-]\):**

\[ 4.250 = \text{p}K_a + \log \left( \frac{[\text{A}^-]}{0.117} \right) \]

3. **Determine the concentration of \([\text{A}^-]\) which is the concentration of sodium nitrite.**

4. **Calculate the moles of sodium nitrite required:**

\[ \text{Moles of sodium nitrite} = \text{Concentration} \times \text{Volume} \]

5. **Convert moles to grams:**

\[ \text{Grams of sodium nitrite} = \text{Moles} \times \text{Molar Mass} \]

Insert the numbers accordingly and solve for the mass of sodium nitrite needed.

**Input Field:**

\[ \boxed{ \phantom{000} } \, \text{g sodium nitrite} \]

**Note:** 
This explanation does not include a graph or diagram
Transcribed Image Text:**Buffer Solution Preparation Calculation** **Problem Statement:** How many grams of solid sodium nitrite should be added to 2.00 L of 0.117 M nitrous acid solution to prepare a buffer with a pH of 4.250? ( \( K_a \) for nitrous acid = \( 4.50 \times 10^{-4} \) ) **Solution:** To solve this problem, we will use the Henderson-Hasselbalch equation for buffer solutions: \[ \text{pH} = \text{p}K_a + \log \left( \frac{[\text{A}^-]}{[\text{HA}]} \right) \] Where: - \( \text{pH} \) is the desired pH of the buffer solution. - \( \text{p}K_a \) is the negative logarithm of the acid dissociation constant (\( K_a \)). - \([\text{A}^-]\) is the concentration of the conjugate base. - \([\text{HA}]\) is the concentration of the weak acid. 1. **Calculate \( \text{p}K_a \):** \[ \text{p}K_a = -\log ( 4.50 \times 10^{-4} ) \] 2. **Set up the Henderson-Hasselbalch equation and solve for \([\text{A}^-]\):** \[ 4.250 = \text{p}K_a + \log \left( \frac{[\text{A}^-]}{0.117} \right) \] 3. **Determine the concentration of \([\text{A}^-]\) which is the concentration of sodium nitrite.** 4. **Calculate the moles of sodium nitrite required:** \[ \text{Moles of sodium nitrite} = \text{Concentration} \times \text{Volume} \] 5. **Convert moles to grams:** \[ \text{Grams of sodium nitrite} = \text{Moles} \times \text{Molar Mass} \] Insert the numbers accordingly and solve for the mass of sodium nitrite needed. **Input Field:** \[ \boxed{ \phantom{000} } \, \text{g sodium nitrite} \] **Note:** This explanation does not include a graph or diagram
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