Textbook Question
b. How does the presence of an electronegative substituent such as Cl affect the acidity of a carboxylic acid?
c. How does the location of the substituent affect the acidity of the carboxylic acid?
Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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Table of contents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)31
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)65
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
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Bruice 8th EditionCh. 2 - Acids and Bases: Central to Understanding Organic ChemistryProblem 60a
Bruice 8th EditionCh. 2 - Acids and Bases: Central to Understanding Organic ChemistryProblem 60aChapter 3, Problem 60a
For each of the following compounds, draw the form that predominates at pH = 3, pH = 6, pH = 10, and pH = 14:
a. CH3COOH (pKa = 4.8)
Verified step by step guidance1
Step 1: Understand the relationship between pH and pKa. The Henderson-Hasselbalch equation, \( \text{pH} = \text{pKa} + \log \left( \frac{[\text{A}^-]}{[\text{HA}]} \right) \), helps determine the ratio of the deprotonated form \( [\text{A}^-] \) to the protonated form \( [\text{HA}] \). When \( \text{pH} < \text{pKa} \), the protonated form \( [\text{HA}] \) predominates, and when \( \text{pH} > \text{pKa} \), the deprotonated form \( [\text{A}^-] \) predominates.
Step 2: Analyze the compound CH3COOH (acetic acid). Acetic acid is a weak acid with a \( \text{pKa} = 4.8 \). The protonated form is \( \text{CH}_3\text{COOH} \), and the deprotonated form is \( \text{CH}_3\text{COO}^- \).
Step 3: Determine the predominant form at \( \text{pH} = 3 \). Since \( \text{pH} = 3 \) is less than \( \text{pKa} = 4.8 \), the protonated form \( \text{CH}_3\text{COOH} \) will predominate.
Step 4: Determine the predominant form at \( \text{pH} = 6 \). Since \( \text{pH} = 6 \) is greater than \( \text{pKa} = 4.8 \), the deprotonated form \( \text{CH}_3\text{COO}^- \) will predominate.
Step 5: Determine the predominant forms at \( \text{pH} = 10 \) and \( \text{pH} = 14 \). Both \( \text{pH} = 10 \) and \( \text{pH} = 14 \) are much greater than \( \text{pKa} = 4.8 \), so the deprotonated form \( \text{CH}_3\text{COO}^- \) will predominate in both cases.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Acid-Base Equilibrium
Acid-base equilibrium refers to the balance between the protonated (acid) and deprotonated (base) forms of a compound in solution. The pKa value indicates the pH at which half of the acid is dissociated. Understanding this equilibrium is crucial for predicting the predominant form of a compound at different pH levels.
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Determining Acid/Base Equilibrium
pH Scale
The pH scale measures the acidity or basicity of a solution, ranging from 0 (very acidic) to 14 (very basic), with 7 being neutral. The pH affects the ionization of acids and bases, influencing their chemical behavior. Knowing the pH of a solution helps determine whether a compound exists primarily in its protonated or deprotonated form.
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02:15The pH scale vs. the pKa scale.
Dissociation of Acids
Dissociation of acids involves the release of protons (H+) when an acid is dissolved in water. For weak acids like acetic acid (CH3COOH), the extent of dissociation is influenced by the pH of the solution. At pH values below the pKa, the acid predominates, while at pH values above the pKa, the conjugate base becomes more prevalent.
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04:09How to calculate enthalpy using bond dissociation energies.
Related Practice
Textbook Question
Draw the products of the following reactions:
a.
b.
c.
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Textbook Question
Rank the following compounds from strongest to weakest acid:
CH3CH2OH; CH3CH2NH2; CH3CH2SH; CH3CH2CH3
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Textbook Question
For each of the following compounds, draw the form that predominates at pH = 3, pH = 6, pH = 10, and pH = 14:
c. CF3CH2OH (pKa = 12.4)
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Textbook Question
For each of the following compounds, draw the form that predominates at pH = 3, pH = 6, pH = 10, and pH = 14:
b. CH3CH2N+H3 (pKa = 11.0)
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Textbook Question
Give the products of the following acid–base reactions and indicate whether reactants or products are favored at equilibrium.
a.
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