Textbook Question
a. Propose a mechanism for the free-radical chlorination of ethane,
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Ch.4 - The Study of Chemical Reactions
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 4, Problem 8b
For each reaction, estimate whether ΔS° for the reaction is positive, negative, or impossible to predict.
(b) 
Verified step by step guidance1
Step 1: Understand the concept of entropy (ΔS°). Entropy is a measure of disorder or randomness in a system. A positive ΔS° indicates an increase in disorder, while a negative ΔS° indicates a decrease in disorder.
Step 2: Analyze the reaction. The formation of diacetone alcohol involves combining smaller molecules into a larger, more complex molecule. This typically results in a decrease in the number of particles in the system.
Step 3: Consider the physical states of the reactants and products. If the reactants are in a more disordered state (e.g., gases or liquids) and the product is a single, more ordered molecule, this suggests a decrease in entropy.
Step 4: Evaluate the role of the hydroxide ion (OH⁻). The hydroxide ion acts as a catalyst in this reaction, meaning it facilitates the reaction without being consumed. Its presence does not significantly affect the entropy change of the system.
Step 5: Conclude based on the above analysis. Since the reaction involves the formation of a larger molecule from smaller ones, ΔS° for the reaction is likely negative, as the system becomes more ordered.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Entropy (ΔS°)
Entropy, denoted as ΔS°, is a measure of the disorder or randomness in a system. In chemical reactions, a positive ΔS° indicates an increase in disorder, while a negative ΔS° suggests a decrease in disorder. Understanding how the number of moles of gaseous products and reactants changes during a reaction is crucial for predicting the sign of ΔS°.
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02:46
Explaining what entropy is.
Reaction Mechanism
The reaction mechanism describes the step-by-step process by which reactants are converted into products. In the case of diacetone alcohol formation, knowing the intermediates and the overall stoichiometry helps in assessing how the arrangement of molecules changes, which directly influences the entropy change.
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Equilibrium and Le Chatelier's Principle
Le Chatelier's Principle states that if a system at equilibrium is disturbed, it will shift in a direction that counteracts the disturbance. This principle can help predict how changes in concentration, temperature, or pressure affect the position of equilibrium and, consequently, the entropy of the system during the formation of diacetone alcohol.
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Related Practice
Textbook Question
When ethene is mixed with hydrogen in the presence of a platinum catalyst, hydrogen adds across the double bond to form ethane. At room temperature, the reaction goes to completion. Predict the signs of ΔH° and ΔS° for this reaction. Explain these signs in terms of bonding and freedom of motion.
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Textbook Question
b. Calculate ΔH° for each step in this reaction.
c. Calculate the overall value of ΔH° for this reaction.
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Textbook Question
For each reaction, estimate whether ΔS° for the reaction is positive, negative, or impossible to predict.
(a)
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Textbook Question
Draw a reaction-energy diagram for the propagation steps of the free-radical addition of HBr to isobutylene. Draw curves representing the reactions leading to both the Markovnikov and the anti-Markovnikov products. Compare the values of ∆Gº and Ea and for the rate-limiting steps, and explain why only one of these products is observed.
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Textbook Question
For each reaction, estimate whether ΔS° for the reaction is positive, negative, or impossible to predict.
(c)
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