Textbook Question
From which of the following compounds can HO− remove a proton in a reaction that favors product formation?
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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 68b(1)
Bruice 8th EditionCh. 2 - Acids and Bases: Central to Understanding Organic ChemistryProblem 68b(1)Chapter 3, Problem 68b(1)
Which of the four reactions has the most favorable equilibrium constant?
1. 
Verified step by step guidance1
Step 1: Understand the problem. The problem involves comparing the equilibrium constants of two reactions: (1) CH3CH2OH + NH3 ⇌ CH3CH2O⁻ + NH4⁺ and (2) CH3OH + NH3 ⇌ CH3O⁻ + NH4⁺. The equilibrium constant depends on the relative acidities (pKa values) of the alcohols (CH3CH2OH and CH3OH) and the base NH3.
Step 2: Recall the relationship between pKa and equilibrium. The equilibrium constant (Keq) for an acid-base reaction is related to the difference in pKa values of the acid and conjugate acid. Specifically, Keq increases as the pKa of the acid decreases (stronger acid) or as the pKa of the conjugate acid increases (weaker conjugate acid).
Step 3: Compare the acidities of CH3CH2OH and CH3OH. Ethanol (CH3CH2OH) and methanol (CH3OH) are both alcohols, but methanol is slightly more acidic than ethanol. This means CH3OH has a lower pKa than CH3CH2OH, making it a stronger acid.
Step 4: Analyze the equilibrium constants. Since CH3OH is a stronger acid than CH3CH2OH, the reaction involving CH3OH (CH3OH + NH3 ⇌ CH3O⁻ + NH4⁺) will have a more favorable equilibrium constant compared to the reaction involving CH3CH2OH.
Step 5: Conclude the comparison. The reaction CH3OH + NH3 ⇌ CH3O⁻ + NH4⁺ has the most favorable equilibrium constant because methanol (CH3OH) is a stronger acid than ethanol (CH3CH2OH), leading to a greater tendency to donate a proton to NH3.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Equilibrium Constant (K)
The equilibrium constant (K) quantifies the ratio of the concentrations of products to reactants at equilibrium for a reversible reaction. A larger K value indicates a greater tendency for the reaction to favor products, while a smaller K suggests a preference for reactants. Understanding K is crucial for predicting the direction and extent of a reaction's progress.
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02:19
The relationship between equilibrium constant and pKa.
Acid-Base Reactions
Acid-base reactions involve the transfer of protons (H+) between species. In the context of the given reactions, ethanol (CH3CH2OH) and methanol (CH3OH) act as weak acids, while ammonia (NH3) serves as a base. The strength of the acids and bases involved influences the equilibrium position and the resulting equilibrium constant.
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02:49The Lewis definition of acids and bases.
Le Chatelier's Principle
Le Chatelier's Principle states that if a system at equilibrium is disturbed, the system will adjust to counteract the disturbance and restore a new equilibrium. This principle helps predict how changes in concentration, pressure, or temperature will affect the position of equilibrium, which is essential for analyzing the favorability of the reactions in question.
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04:12The Electron Configuration
Related Practice
Textbook Question
Tenormin, a member of the group of drugs known as beta-blockers, is used to treat high blood pressure and improve survival after a heart attack. It works by slowing down the heart to reduce its workload. Which atom in Tenormin is the most basic?
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Textbook Question
For each of the following pairs of reactions, indicate which one has the more favorable equilibrium constant (that is, which one most favors products):
1.
2.
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Textbook Question
a. Without using a calculator, estimate the pH of each of the following solutions:
1. [HO−] = 3.2 × 10−5
2. [H3O+] = 8.3 × 10−1
3. [H3O+] = 1.7 × 10−3
b. Determine the exact pH, using a calculator.
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Textbook Question
Citrus fruits are rich in citric acid, a compound with three COOH groups. Explain the following:
a. The first pKa (for the COOH group in the center of the molecule) is lower than the pKa of acetic acid.
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Textbook Question
You are planning to carry out a reaction that produces protons. The reaction will be buffered at pH = 10.5. Would it be better to use a protonated methylamine/methylamine buffer or a protonated ethylamine/ethylamine buffer? (pKa of protonated methylamine = 10.7; pKa of protonated ethylamine = 11.0)
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