A chemistry graduate student is given 500. mL of a 0.40M ammonia (NH,) solution. Ammonia is a weak base with K,=1.8 × 10 What mass of NH,Cl should the student dissolve in the NH, solution to turn it into a buffer with pH =8.99? You may assume that the volume of the solution doesn't change when the NH,Cl is dissolved in it. Be sure your answer has a unit symbol, and round it to 2 significant digits.
A chemistry graduate student is given 500. mL of a 0.40M ammonia (NH,) solution. Ammonia is a weak base with K,=1.8 × 10 What mass of NH,Cl should the student dissolve in the NH, solution to turn it into a buffer with pH =8.99? You may assume that the volume of the solution doesn't change when the NH,Cl is dissolved in it. Be sure your answer has a unit symbol, and round it to 2 significant digits.
Chemistry: Principles and Practice
3rd Edition
ISBN:9780534420123
Author:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward Mercer
Publisher:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward Mercer
Chapter16: Reactions Between Acids And Bases
Section: Chapter Questions
Problem 16.7QE
Related questions
Question
![**Buffer Solution Calculation**
**Problem Statement:**
A chemistry graduate student is given 500. mL of a 0.40 M ammonia (NH₃) solution. Ammonia is a weak base with \( K_b = 1.8 \times 10^{-5} \). What mass of NH₄Cl should the student dissolve in the NH₃ solution to turn it into a buffer with \( \text{pH} = 8.99 \)?
**Assumptions:**
- The volume of the solution does not change when NH₄Cl is dissolved.
- Provide the answer in units and rounded to 2 significant digits.
In the given image, there appears to be a placeholder input field and multiple choice interaction widgets below the problem statement, which typically might be used in an online learning platform to capture students' calculations or responses.
To solve this problem, we can follow these steps:
1. **Write the Chemical Equilibrium Expression for NH₃:**
\[ \text{NH₃} + \text{H₂O} \rightleftharpoons \text{NH₄}^+ + \text{OH}^- \]
2. **Calculate the pOH and [OH⁻]:**
\[ \text{pH} = 8.99 \]
\[ \text{pOH} = 14 - \text{pH} \]
\[ \text{pOH} = 14 - 8.99 = 5.01 \]
\[ [\text{OH}^-] = 10^{-\text{pOH}} = 10^{-5.01} \]
3. **Calculate the [NH₄⁺]:**
Using the Henderson-Hasselbalch equation for bases:
\[ \text{pOH} = \text{p}K_b + \log\left(\frac{[\text{NH₄}^+]}{[\text{NH₃}]}\right) \]
Rearrange to find \([\text{NH₄}^+]\):
\[ 5.01 = -\log(1.8 \times 10^{-5}) + \log\left(\frac{[\text{NH₄}^+]}{0.40}\right) \]
Calculate \(\text{p}K](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F868a318f-0624-4ed5-b0cc-007ff8576a9b%2F28e33332-6d33-4a87-8480-9ed08c5447ff%2Fxp7f36a_processed.png&w=3840&q=75)
Transcribed Image Text:**Buffer Solution Calculation**
**Problem Statement:**
A chemistry graduate student is given 500. mL of a 0.40 M ammonia (NH₃) solution. Ammonia is a weak base with \( K_b = 1.8 \times 10^{-5} \). What mass of NH₄Cl should the student dissolve in the NH₃ solution to turn it into a buffer with \( \text{pH} = 8.99 \)?
**Assumptions:**
- The volume of the solution does not change when NH₄Cl is dissolved.
- Provide the answer in units and rounded to 2 significant digits.
In the given image, there appears to be a placeholder input field and multiple choice interaction widgets below the problem statement, which typically might be used in an online learning platform to capture students' calculations or responses.
To solve this problem, we can follow these steps:
1. **Write the Chemical Equilibrium Expression for NH₃:**
\[ \text{NH₃} + \text{H₂O} \rightleftharpoons \text{NH₄}^+ + \text{OH}^- \]
2. **Calculate the pOH and [OH⁻]:**
\[ \text{pH} = 8.99 \]
\[ \text{pOH} = 14 - \text{pH} \]
\[ \text{pOH} = 14 - 8.99 = 5.01 \]
\[ [\text{OH}^-] = 10^{-\text{pOH}} = 10^{-5.01} \]
3. **Calculate the [NH₄⁺]:**
Using the Henderson-Hasselbalch equation for bases:
\[ \text{pOH} = \text{p}K_b + \log\left(\frac{[\text{NH₄}^+]}{[\text{NH₃}]}\right) \]
Rearrange to find \([\text{NH₄}^+]\):
\[ 5.01 = -\log(1.8 \times 10^{-5}) + \log\left(\frac{[\text{NH₄}^+]}{0.40}\right) \]
Calculate \(\text{p}K
Expert Solution
This question has been solved!
Explore an expertly crafted, step-by-step solution for a thorough understanding of key concepts.
Step by step
Solved in 2 steps
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, chemistry and related others by exploring similar questions and additional content below.Recommended textbooks for you
Chemistry: Principles and Practice
Chemistry
ISBN:
9780534420123
Author:
Daniel L. Reger, Scott R. Goode, David W. Ball, Edward Mercer
Publisher:
Cengage Learning
Chemistry
Chemistry
ISBN:
9781305957404
Author:
Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:
Cengage Learning
Chemistry: An Atoms First Approach
Chemistry
ISBN:
9781305079243
Author:
Steven S. Zumdahl, Susan A. Zumdahl
Publisher:
Cengage Learning
Chemistry: Principles and Practice
Chemistry
ISBN:
9780534420123
Author:
Daniel L. Reger, Scott R. Goode, David W. Ball, Edward Mercer
Publisher:
Cengage Learning
Chemistry
Chemistry
ISBN:
9781305957404
Author:
Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:
Cengage Learning
Chemistry: An Atoms First Approach
Chemistry
ISBN:
9781305079243
Author:
Steven S. Zumdahl, Susan A. Zumdahl
Publisher:
Cengage Learning
Principles of Modern Chemistry
Chemistry
ISBN:
9781305079113
Author:
David W. Oxtoby, H. Pat Gillis, Laurie J. Butler
Publisher:
Cengage Learning
