Textbook Question
The following compounds can all react as bases.
a. For each compound, show its conjugate acid. Show any resonance forms if applicable.
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Ch. 2 - Acids and Bases; Functional Groups
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 2, Problem 44
Compare the relative acidity of 1-molar aqueous solutions of the following acids.
Verified step by step guidance1
Identify the concept of acidity in terms of pKa values: The lower the pKa value, the stronger the acid.
List the given acids along with their pKa values: NH4Cl (pKa=9.26), CH3COOH (pKa=4.74), BrCH2COOH (pKa=2.9), F3CCOOH (pKa=0.2), H2SO4 (pKa=-5), HCl (pKa=-7), HBr (pKa=-9).
Arrange the acids in order of increasing acidity based on their pKa values. Start with the highest pKa value (weakest acid) and end with the lowest pKa value (strongest acid).
Compare the acids: NH4Cl is the weakest acid with the highest pKa, while HBr is the strongest acid with the lowest pKa.
Conclude the comparison by stating that the order of acidity from weakest to strongest is: NH4Cl, CH3COOH, BrCH2COOH, F3CCOOH, H2SO4, HCl, HBr.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
pKa and Acidity
The pKa value is a measure of the strength of an acid in solution. It represents the negative logarithm of the acid dissociation constant (Ka). A lower pKa value indicates a stronger acid, as it implies a greater tendency to donate protons. In comparing acids, the one with the lowest pKa is the strongest acid.
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Identifying pKa values
Inductive Effect
The inductive effect refers to the electron-withdrawing or electron-donating effects exerted by substituents through sigma bonds. Electronegative atoms or groups, such as fluorine in F3CCOOH, can stabilize the negative charge on the conjugate base, increasing the acid's strength. This effect is crucial in understanding why some acids are stronger than others.
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01:47Understanding the Inductive Effect.
Comparing Acid Strengths
To compare the relative acidity of different acids, one must consider both the pKa values and the molecular structure. Acids with lower pKa values are stronger. Additionally, structural factors like the presence of electronegative atoms or resonance stabilization of the conjugate base can significantly influence acidity. For example, HCl and HBr are strong acids due to their very low pKa values and the stability of their conjugate bases.
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Related Practice
Textbook Question
Predict the products of the following acid–base reactions.
(h)
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Textbook Question
The following compounds can all react as acids.
a. For each compound, show its conjugate base. Show any resonance forms if applicable. b. Rank the conjugate bases in the order you would predict, from most stable to least stable.
1
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Textbook Question
Consider the following proposed Brønsted–Lowry acid–base reactions. In each case, draw the products of a transfer of the most acidic proton on the acid to the most basic site on the base. Use Appendix 4 to find or estimate the pKa values for the acids and the pKb values for the bases. Then determine which side of the reaction is favored, either reactants or products.
(a)
(b)
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Textbook Question
Predict the products of the following acid–base reactions.
(g) HCOOH + CH3O– ⇌
Textbook Question
The following compounds can all react as acids.
c. Rank the original compounds in order, from strongest acid to weakest acid.