Textbook Question
Write the Keq expression for the following acid–base reactions. [You don't need to calculate Keq here.]
(c)
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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 22b
Given the value of Keq for the following acid–base reactions, identify the weakest acid and the weakest base.
(b) 
Verified step by step guidance1
Step 1: Analyze the reaction provided. The reaction involves ethyllithium (H₃C–CH₂Li) reacting with water (H₂O) to produce ethane (H₃C–CH₃) and lithium hydroxide (HO⁻Li⁺). The equilibrium constant (K_eq) is given as 2.0 × 10⁴⁴, which is extremely large, indicating the reaction strongly favors the products.
Step 2: Recall the relationship between acid strength and conjugate base strength. A strong acid has a weak conjugate base, and a weak acid has a strong conjugate base. Similarly, a strong base has a weak conjugate acid, and a weak base has a strong conjugate acid.
Step 3: Identify the acids and bases in the reaction. In this case, ethyllithium acts as the base, and water acts as the acid. On the product side, ethane is the conjugate acid of ethyllithium, and lithium hydroxide is the conjugate base of water.
Step 4: Use the K_eq value to determine the relative strengths. Since K_eq is extremely large, the reaction strongly favors the formation of ethane and lithium hydroxide. This implies that ethane is a very weak acid and lithium hydroxide is a very weak base compared to their counterparts on the reactant side.
Step 5: Conclude that the weakest acid in the reaction is ethane (H₃C–CH₃), and the weakest base in the reaction is lithium hydroxide (HO⁻Li⁺).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Equilibrium Constant (K_eq)
The equilibrium constant (K_eq) quantifies the ratio of the concentrations of products to reactants at equilibrium for a given reaction. A large K_eq value, such as 2.0 x 10^44, indicates that the products are favored, suggesting that the reaction proceeds almost to completion. This concept is crucial for determining the strength of acids and bases in a reaction.
Recommended video:
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02:19
The relationship between equilibrium constant and pKa.
Acid-Base Strength
Acid-base strength is determined by the ability of an acid to donate protons (H+) and a base to accept protons. In a reaction, the weaker acid corresponds to the stronger base, as the equilibrium favors the formation of the weaker acid and base. Understanding this relationship is essential for identifying the weakest acid and base in the given reaction.
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Reaction Products
In acid-base reactions, the products formed can provide insight into the relative strengths of the reactants. For instance, in the reaction shown, ethane and lithium hydroxide are produced, indicating that ethyllithium acts as a strong base and water as a weak acid. Analyzing the products helps in determining which reactant is the weakest acid and base.
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Related Practice
Textbook Question
Given the Keq values for the following acid–base reactions, identify the strongest acid and the strongest base.
(a)
1113
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Textbook Question
In the following reactions,
(i) identify the acid and base,
(ii) identify the most electron-rich atom in the base,
(iii) identify the most acidic hydrogen in the acid,
(iv) provide an arrow-pushing mechanism of the proton transfer that will occur, and
(v) predict the product of the reactions. [You'll need to provide the lone pairs here.]
(d) H2O + HCl ⇌
638
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Textbook Question
Given the value of Keq for the following acid–base reactions, identify the weakest acid and the weakest base.
(a)
986
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Textbook Question
Given the value of Keq for the following acid–base reactions, identify the weakest acid and the weakest base.
(c)
1114
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Textbook Question
Given the Keq values for the following acid–base reactions, identify the strongest acid and the strongest base.
(b)
1112
views