Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

6. Thermodynamics and Kinetics

Entropy

Organic Chemistry

6. Thermodynamics and Kinetics

Entropy

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3:11 minutes

Problem 8c

Textbook Question

For each reaction, estimate whether ΔS° for the reaction is positive, negative, or impossible to predict.
(c)

Verified step by step guidance

Analyze the reaction: The reaction involves the conversion of acetic acid (CH3COOH) and methanol (CH3OH) into methyl acetate (CH3COOCH3) and water (H2O). This is an esterification reaction.

Consider the number of molecules on each side: On the reactant side, there are two molecules (CH3COOH and CH3OH). On the product side, there are also two molecules (CH3COOCH3 and H2O). Since the number of molecules remains the same, there is no significant change in the positional entropy due to the number of particles.

Evaluate the structural changes: The reactants are a carboxylic acid and an alcohol, while the products are an ester and water. The formation of an ester involves the creation of a more ordered structure, which may slightly decrease entropy.

Consider the phase of the reactants and products: If all species are in the same phase (e.g., liquid), the entropy change due to phase differences is negligible. However, if there are phase changes, this could influence ΔS°.

Conclude the trend: Based on the structural ordering and the lack of change in the number of molecules, ΔS° for this reaction is likely to be slightly negative due to the formation of a more ordered ester structure.

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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 and liquid products and reactants changes during a reaction is crucial for predicting the sign of ΔS°.

Reaction Stoichiometry

Reaction stoichiometry involves the quantitative relationships between reactants and products in a chemical reaction. In the given reaction, analyzing the number of molecules and their states (liquid, gas) helps determine how the overall disorder changes. For example, if more molecules are produced than consumed, the reaction likely has a positive ΔS°.

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. In the context of the given reaction, understanding how the equilibrium position affects the concentrations of reactants and products can provide insights into the entropy changes. This principle is essential for predicting how changes in conditions might influence ΔS°.

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Related Practice

Textbook Question

For the following values of ∆H° , ∆S°, and T, tell whether the process would be favored.

(a) ∆H° = -15 kcal/mol ; ∆S° = +37 cal/mol•K ; T = 273 K

Textbook Question

For each reaction, estimate whether ΔS° for the reaction is positive, negative, or impossible to predict.

(a)

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.

Textbook Question

For each reaction, estimate whether ΔS° for the reaction is positive, negative, or impossible to predict.

(b)

Textbook Question

a. For which reaction in each set will ∆S° be more significant?

b. For which reaction will ∆S° be positive?

1. A ⇌ B or A + B ⇌ C

2. A ⇌ B + C or A + B ⇌ C + D

Textbook Question

a. Which of the following reactions has the larger ∆S° value?

b. Is the ∆S° value positive or negative?

Textbook Question