Consider a buffer made by adding 55.5 g of (CH3)2NH2I to 250.0 mL of 1.42 M (CH3)2NH (Kb = 5.4 x 10-4) What is the pH of the buffer after 0.300 mol of H* have been added?
Consider a buffer made by adding 55.5 g of (CH3)2NH2I to 250.0 mL of 1.42 M (CH3)2NH (Kb = 5.4 x 10-4) What is the pH of the buffer after 0.300 mol of H* have been added?
Chapter8: Polyfunctional Acids And Bases
Section: Chapter Questions
Problem 6P
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![### Buffer Solution pH Calculation
#### Problem Statement:
Consider a buffer made by adding 55.5 g of \((CH_3)_2NH_2I\) to 250.0 mL of 1.42 M \((CH_3)_2NH\) (Kb = \(5.4 \times 10^{-4}\)).
What is the pH of the buffer after 0.300 mol of \(H^+\) have been added?
#### Explanation:
To solve this problem, you'll need to follow these steps:
1. **Determine the moles of \((CH_3)_2NH_2I\) and \((CH_3)_2NH\)**:
- Moles of \((CH_3)_2NH_2I\): Calculate using the molar mass.
- Moles of \((CH_3)_2NH\): Calculate using concentration and volume.
2. **Set up the buffer equation (Henderson-Hasselbalch equation)**:
- Henderson-Hasselbalch equation:
\[ \text{pH} = \text{p}K_a + \log \left( \frac{[\text{Base}]}{[\text{Acid}]} \right) \]
- \( \text{p}K_a \) is calculated using the \( K_b \).
3. **Adjust for the added \( H^+ \)**:
- Update the concentrations of acid and base after adding the \( H^+ \).
4. **Calculate the new pH**:
- Substitute the updated concentrations into the Henderson-Hasselbalch equation to find the new pH.
#### Graphs and Diagrams:
- **Numeric Keypad**:
A numeric keypad is shown with digits 0-9, basic operations, and a 'C' (clear) button, likely for calculations.
It is essential to approach the pH calculation step by step, ensuring all correct molar masses, volumes, and concentrations are used.
#### Conclusion:
Understanding buffer solutions and the pH calculation through the Henderson-Hasselbalch equation is crucial in chemistry. By methodically following the steps outlined above, you can determine the pH of the buffer after the addition of \( H^+ \).
### Example Calculation (Hypothetical):
1. **Calculate Moles of \((CH_3)_](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fabf3f71a-8f38-4387-af5c-ba72dda07b09%2F18840c26-ff31-4055-8b61-026bf02af684%2Fd9c1bx9_processed.png&w=3840&q=75)
Transcribed Image Text:### Buffer Solution pH Calculation
#### Problem Statement:
Consider a buffer made by adding 55.5 g of \((CH_3)_2NH_2I\) to 250.0 mL of 1.42 M \((CH_3)_2NH\) (Kb = \(5.4 \times 10^{-4}\)).
What is the pH of the buffer after 0.300 mol of \(H^+\) have been added?
#### Explanation:
To solve this problem, you'll need to follow these steps:
1. **Determine the moles of \((CH_3)_2NH_2I\) and \((CH_3)_2NH\)**:
- Moles of \((CH_3)_2NH_2I\): Calculate using the molar mass.
- Moles of \((CH_3)_2NH\): Calculate using concentration and volume.
2. **Set up the buffer equation (Henderson-Hasselbalch equation)**:
- Henderson-Hasselbalch equation:
\[ \text{pH} = \text{p}K_a + \log \left( \frac{[\text{Base}]}{[\text{Acid}]} \right) \]
- \( \text{p}K_a \) is calculated using the \( K_b \).
3. **Adjust for the added \( H^+ \)**:
- Update the concentrations of acid and base after adding the \( H^+ \).
4. **Calculate the new pH**:
- Substitute the updated concentrations into the Henderson-Hasselbalch equation to find the new pH.
#### Graphs and Diagrams:
- **Numeric Keypad**:
A numeric keypad is shown with digits 0-9, basic operations, and a 'C' (clear) button, likely for calculations.
It is essential to approach the pH calculation step by step, ensuring all correct molar masses, volumes, and concentrations are used.
#### Conclusion:
Understanding buffer solutions and the pH calculation through the Henderson-Hasselbalch equation is crucial in chemistry. By methodically following the steps outlined above, you can determine the pH of the buffer after the addition of \( H^+ \).
### Example Calculation (Hypothetical):
1. **Calculate Moles of \((CH_3)_
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