What is the pH of a 1.0 L buffer made with 0.300 mol of HF (Ka = 6.8 × 10-4) and 0.200 mol of NaF to which 0.110 mol of NaOH were added?

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### Buffer pH Calculation for Educational Purposes

#### Problem Statement:
What is the pH of a 1.0 L buffer made with 0.300 mol of HF (Ka = 6.8 x 10^-4) and 0.200 mol of NaF to which 0.110 mol of NaOH were added?

#### Background:
A buffer solution is essential in maintaining pH stability, composed typically of a weak acid and its conjugate base. In this scenario, the weak acid is hydrofluoric acid (HF), and its conjugate base is sodium fluoride (NaF). The addition of sodium hydroxide (NaOH), a strong base, will shift the equilibrium and affect the pH of the buffer solution.

#### Approach:
1. **Initial Concentration Calculations:**
   - **HF (Weak Acid):** Initially, we have 0.300 mol of HF in 1.0 L, so the initial concentration of HF is 0.300 M.
   - **NaF (Conjugate Base):** Initially, we have 0.200 mol of NaF in 1.0 L, so the initial concentration of NaF is 0.200 M.

2. **Reaction with NaOH:**
   - Upon adding 0.110 mol of NaOH, a strong base, it reacts completely with HF:
   \[
   \text{HF} + \text{NaOH} \rightarrow \text{H}_2\text{O} + \text{NaF}
   \]
   - Mole of HF after reaction: 0.300 mol (initial) - 0.110 mol (reacted) = 0.190 mol
   - Mole of NaF formed from reaction: 0.200 mol (initial) + 0.110 mol (formed) = 0.310 mol

3. **New Concentrations:**
   - **HF:** 0.190 mol / 1.0 L = 0.190 M
   - **NaF:** 0.310 mol / 1.0 L = 0.310 M

4. **Henderson-Hasselbalch Equation:**
   The pH of the buffer solution can be calculated using the Henderson-Hasselbalch Equation:
    \[
    \text{pH} = \text{p}K_\text{a}
Transcribed Image Text:### Buffer pH Calculation for Educational Purposes #### Problem Statement: What is the pH of a 1.0 L buffer made with 0.300 mol of HF (Ka = 6.8 x 10^-4) and 0.200 mol of NaF to which 0.110 mol of NaOH were added? #### Background: A buffer solution is essential in maintaining pH stability, composed typically of a weak acid and its conjugate base. In this scenario, the weak acid is hydrofluoric acid (HF), and its conjugate base is sodium fluoride (NaF). The addition of sodium hydroxide (NaOH), a strong base, will shift the equilibrium and affect the pH of the buffer solution. #### Approach: 1. **Initial Concentration Calculations:** - **HF (Weak Acid):** Initially, we have 0.300 mol of HF in 1.0 L, so the initial concentration of HF is 0.300 M. - **NaF (Conjugate Base):** Initially, we have 0.200 mol of NaF in 1.0 L, so the initial concentration of NaF is 0.200 M. 2. **Reaction with NaOH:** - Upon adding 0.110 mol of NaOH, a strong base, it reacts completely with HF: \[ \text{HF} + \text{NaOH} \rightarrow \text{H}_2\text{O} + \text{NaF} \] - Mole of HF after reaction: 0.300 mol (initial) - 0.110 mol (reacted) = 0.190 mol - Mole of NaF formed from reaction: 0.200 mol (initial) + 0.110 mol (formed) = 0.310 mol 3. **New Concentrations:** - **HF:** 0.190 mol / 1.0 L = 0.190 M - **NaF:** 0.310 mol / 1.0 L = 0.310 M 4. **Henderson-Hasselbalch Equation:** The pH of the buffer solution can be calculated using the Henderson-Hasselbalch Equation: \[ \text{pH} = \text{p}K_\text{a}
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