Phenylacetic acid (C6H₂CH₂CO₂H) is a weak monoprotic acid with K₂ = 4.90 x 10-5. What is the pH of a 9.21 x 10-¹ M solution of potassium phenylacetate (CH₂CH₂CO₂K* )?

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...
icon
Related questions
Question
100%
**Topic: Calculating the pH of a Weak Acid Solution**

Phenylacetic acid (\(C_6H_5CH_2CO_2H\)) is a weak monoprotic acid with an acid dissociation constant (\(K_a\)) of \(4.90 \times 10^{-5}\). The task is to determine the pH of a \(9.21 \times 10^{-1} \, M\) solution of potassium phenylacetate (\(C_6H_5CH_2CO_2^− K^+\)).

**Context:**

When salts like potassium phenylacetate are dissolved in water, they dissociate into ions. In this case, the phenylacetate ion (\(C_6H_5CH_2CO_2^−\)) acts as a conjugate base and can accept a proton (\(H^+\)) from water, forming phenylacetic acid and a hydroxide ion (\(OH^−\)). This results in a basic solution. 

The pH of such a solution can be calculated by considering the hydrolysis reaction and using the relationship between \(K_a\) and \(K_b\) (the base dissociation constant), given by:

\[ K_w = K_a \times K_b \]

where \(K_w\) is the ion-product constant of water (\(1.0 \times 10^{-14}\)). By calculating \(K_b\), we can determine the \(OH^−\) concentration and subsequently the pH.
Transcribed Image Text:**Topic: Calculating the pH of a Weak Acid Solution** Phenylacetic acid (\(C_6H_5CH_2CO_2H\)) is a weak monoprotic acid with an acid dissociation constant (\(K_a\)) of \(4.90 \times 10^{-5}\). The task is to determine the pH of a \(9.21 \times 10^{-1} \, M\) solution of potassium phenylacetate (\(C_6H_5CH_2CO_2^− K^+\)). **Context:** When salts like potassium phenylacetate are dissolved in water, they dissociate into ions. In this case, the phenylacetate ion (\(C_6H_5CH_2CO_2^−\)) acts as a conjugate base and can accept a proton (\(H^+\)) from water, forming phenylacetic acid and a hydroxide ion (\(OH^−\)). This results in a basic solution. The pH of such a solution can be calculated by considering the hydrolysis reaction and using the relationship between \(K_a\) and \(K_b\) (the base dissociation constant), given by: \[ K_w = K_a \times K_b \] where \(K_w\) is the ion-product constant of water (\(1.0 \times 10^{-14}\)). By calculating \(K_b\), we can determine the \(OH^−\) concentration and subsequently the pH.
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 2 steps with 1 images

Blurred answer
Knowledge Booster
Acid-Base Titrations
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.
Similar questions
Recommended textbooks for you
Chemistry
Chemistry
Chemistry
ISBN:
9781305957404
Author:
Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:
Cengage Learning
Chemistry
Chemistry
Chemistry
ISBN:
9781259911156
Author:
Raymond Chang Dr., Jason Overby Professor
Publisher:
McGraw-Hill Education
Principles of Instrumental Analysis
Principles of Instrumental Analysis
Chemistry
ISBN:
9781305577213
Author:
Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher:
Cengage Learning
Organic Chemistry
Organic Chemistry
Chemistry
ISBN:
9780078021558
Author:
Janice Gorzynski Smith Dr.
Publisher:
McGraw-Hill Education
Chemistry: Principles and Reactions
Chemistry: Principles and Reactions
Chemistry
ISBN:
9781305079373
Author:
William L. Masterton, Cecile N. Hurley
Publisher:
Cengage Learning
Elementary Principles of Chemical Processes, Bind…
Elementary Principles of Chemical Processes, Bind…
Chemistry
ISBN:
9781118431221
Author:
Richard M. Felder, Ronald W. Rousseau, Lisa G. Bullard
Publisher:
WILEY