Chemistry
10th Edition
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Chapter1: Chemical Foundations
Section: Chapter Questions
Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
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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}](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F18d0a7dc-afe1-42e7-9349-84d2cfc69c53%2F55fe8214-01ed-454c-bc57-2cb8c29bfaa7%2Fzh4c0qwk_processed.jpeg&w=3840&q=75)
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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