Textbook Question
Given the following Keq values, how much stronger of a base is acetate (CH3CO2-) than chloride (Cl⁻)?
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Ch. 4 - Acids and Bases: Electron Flow
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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Table of contents
- Ch. 2 - General Chemistry Translated: Finding the Electrons114
- Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis109
- Ch. 4 - Acids and Bases: Electron Flow144
- Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics118
- Ch. 6 - Stereoisomerism: Arrangement of Atoms in Space112
- Ch. 7 - Principles of Green (Organic) Chemistry3
- Ch. 8 - Alkenes I: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes II: Oxidation and Reduction150
- Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions101
- Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions108
- Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes172
- Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination239
- Ch. 14 - Structural Identification I: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution I: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution II: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems I: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems II: Pericyclic Reactions54
- Ch. 23 - Benzene I: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring62
- Ch. 25 - Amines: Structure, Reactions, and Synthesis27
- Ch. 26 - Amino Acids, Proteins, and Peptide Synthesis9
- Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids54
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
Chapter 3, Problem 31
Hydrogen gas (H2) has a relatively high pKa value. Is it a stable or unstable acid? Do you expect it to participate in acid–base reactions?
Verified step by step guidance1
Understand the concept of pKₐ: The pKₐ value is a measure of the strength of an acid. A high pKₐ value indicates a weak acid, meaning it does not easily donate protons (H⁺) in solution.
Analyze the pKₐ value of H₂: Hydrogen gas (H₂) has a very high pKₐ value, which suggests that it is an extremely weak acid and does not readily act as a proton donor.
Determine stability: Since H₂ does not easily lose protons, it is considered a stable molecule in terms of acid-base behavior.
Evaluate participation in acid-base reactions: Due to its high pKₐ and weak acidic nature, H₂ is unlikely to participate in acid-base reactions under normal conditions. It is more likely to act as a reducing agent in redox reactions rather than as an acid.
Conclude: Hydrogen gas (H₂) is a stable acid with a high pKₐ value and does not typically participate in acid-base reactions, as it does not readily donate protons.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
pKa Value
The pKa value is a measure of the strength of an acid in solution, indicating how easily it donates protons (H⁺ ions). A high pKa value suggests that the acid is weak and does not dissociate significantly in water, meaning it is less likely to release protons. In the case of hydrogen gas (H₂), its high pKa indicates that it is not a strong acid.
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07:45
Identifying pKa values
Acid Stability
Acid stability refers to the tendency of an acid to remain in its protonated form versus dissociating to release protons. A stable acid will have a lower tendency to lose its protons, while an unstable acid will readily dissociate. Given that H₂ has a high pKa, it is considered a stable acid, as it does not easily participate in acid-base reactions.
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03:43The radical stability trend.
Acid-Base Reactions
Acid-base reactions involve the transfer of protons between species, where acids donate protons and bases accept them. The participation of a substance in these reactions depends on its ability to act as an acid or a base. Since hydrogen gas (H₂) is a weak acid with a high pKa, it is unlikely to participate significantly in acid-base reactions under normal conditions.
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02:49The Lewis definition of acids and bases.
Related Practice
Textbook Question
Using qualitative reasoning for the acid–base reactions shown,
(i) which is stronger, the acid or the conjugate acid?
(ii) Which side of the reaction is favored?
(iii) Would you expect a Keq greater than, equal to, or less than 1?
(a)
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Textbook Question
If a base has a conjugate acid with a high pKa value, is it stable or unstable? How do you know this is true (besides 'I just remember')?
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Textbook Question
Given that the indicated pKa values correspond to the acid dissociation reactions shown, calculate the ratio of acid to conjugate base for the reactions shown.
(a)
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Textbook Question
How do you know that a proton with a low pKa value is acidic (besides 'I just remember')?
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Textbook Question
Given that the indicated pKa values correspond to the acid dissociation reactions shown, calculate the ratio of acid to conjugate base for the reactions shown.
(b)
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