A solution is prepared at 25 °C that is initially 0.12M in acetic acid (HCH,CO,), a weak acid with K,=1.8 × 10 -5 , and 0.046M in sodium acetate (NaCH,CO,). Calculate the pH of the solution. Round your answer to 2 decimal places. pH ?
A solution is prepared at 25 °C that is initially 0.12M in acetic acid (HCH,CO,), a weak acid with K,=1.8 × 10 -5 , and 0.046M in sodium acetate (NaCH,CO,). Calculate the pH of the solution. Round your answer to 2 decimal places. pH ?
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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![**Problem Statement:**
A solution is prepared at 25 °C that is initially 0.12M in acetic acid (HCH₃CO₂), a weak acid with \( K_a = 1.8 \times 10^{-5} \), and 0.046M in sodium acetate (NaCH₃CO₂). Calculate the pH of the solution. Round your answer to 2 decimal places.
---
**Solution:**
To determine the pH of the solution, please follow the steps below:
1. **Identify the formula for pH calculation:**
Since the acetic acid (HCH₃CO₂) and sodium acetate (NaCH₃CO₂) form a buffer solution, we use the Henderson-Hasselbalch equation:
\[
\text{pH} = \text{p}K_a + \log \left( \frac{[\text{Base}]}{[\text{Acid}]} \right)
\]
2. **Calculate the \( \text{p}K_a \):**
\[
\text{p}K_a = -\log (K_a)
\]
Substituting the given value of \( K_a \):
\[
\text{p}K_a = -\log (1.8 \times 10^{-5}) \approx 4.74
\]
3. **Substitute the concentrations into the Henderson-Hasselbalch equation:**
\[
\text{pH} = 4.74 + \log \left( \frac{0.046}{0.12} \right)
\]
4. **Calculate the log term:**
\[
\log \left( \frac{0.046}{0.12} \right) \approx \log (0.383) \approx -0.417
\]
5. **Determine the pH:**
\[
\text{pH} = 4.74 - 0.42 = 4.32
\]
Therefore, the pH of the solution is approximately \( \text{pH} = 4.32 \).
Please enter your result in the provided field (pH = 4.32) on the educational website interface.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F494ae6b1-169d-4d93-a9c8-ab58a11b20bc%2F9dd4b38c-937d-4902-bb66-36ece02222c6%2Ffgopw5i_processed.png&w=3840&q=75)
Transcribed Image Text:**Problem Statement:**
A solution is prepared at 25 °C that is initially 0.12M in acetic acid (HCH₃CO₂), a weak acid with \( K_a = 1.8 \times 10^{-5} \), and 0.046M in sodium acetate (NaCH₃CO₂). Calculate the pH of the solution. Round your answer to 2 decimal places.
---
**Solution:**
To determine the pH of the solution, please follow the steps below:
1. **Identify the formula for pH calculation:**
Since the acetic acid (HCH₃CO₂) and sodium acetate (NaCH₃CO₂) form a buffer solution, we use the Henderson-Hasselbalch equation:
\[
\text{pH} = \text{p}K_a + \log \left( \frac{[\text{Base}]}{[\text{Acid}]} \right)
\]
2. **Calculate the \( \text{p}K_a \):**
\[
\text{p}K_a = -\log (K_a)
\]
Substituting the given value of \( K_a \):
\[
\text{p}K_a = -\log (1.8 \times 10^{-5}) \approx 4.74
\]
3. **Substitute the concentrations into the Henderson-Hasselbalch equation:**
\[
\text{pH} = 4.74 + \log \left( \frac{0.046}{0.12} \right)
\]
4. **Calculate the log term:**
\[
\log \left( \frac{0.046}{0.12} \right) \approx \log (0.383) \approx -0.417
\]
5. **Determine the pH:**
\[
\text{pH} = 4.74 - 0.42 = 4.32
\]
Therefore, the pH of the solution is approximately \( \text{pH} = 4.32 \).
Please enter your result in the provided field (pH = 4.32) on the educational website interface.
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