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

3. Acids and Bases

Acids and Bases

Organic Chemistry

3. Acids and Bases

Acids and Bases

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2:14 minutes

Problem 46a

Textbook Question

The following compounds can all react as bases.

a. For each compound, show its conjugate acid. Show any resonance forms if applicable.

Verified step by step guidance

Identify the base in each compound and determine the site where protonation will occur to form the conjugate acid. For amines like CH3CH2NH2 and CH3CONH2, the nitrogen atom is the basic site. For NaOH and NaNH2, the hydroxide (OH-) and amide (NH2-) ions are the basic sites, respectively. For CH3CH2OH, the oxygen atom in the hydroxyl group is the basic site.

For each compound, add a proton (H+) to the basic site to form the conjugate acid. For example, CH3CH2NH2 becomes CH3CH2NH3+, CH3CONH2 becomes CH3CONH3+, NaOH becomes H2O, CH3CH2OH becomes CH3CH2OH2+, and NaNH2 becomes NH3.

Consider resonance stabilization for each conjugate acid. CH3CONH3+ can have resonance structures due to the carbonyl group adjacent to the nitrogen, which can delocalize the positive charge. This is not possible for the other conjugate acids.

Evaluate the stability of each conjugate acid based on factors such as resonance, electronegativity, and the inductive effect. Resonance-stabilized conjugate acids are generally more stable. The presence of electronegative atoms or groups can also stabilize the positive charge through the inductive effect.

Rank the conjugate acids from most stable to least stable based on the analysis. Consider that resonance and inductive effects play significant roles in determining stability. The more resonance-stabilized or inductively stabilized the conjugate acid, the more stable it is.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Conjugate Acid-Base Pairs

In acid-base chemistry, a conjugate acid-base pair consists of two species that transform into each other by the gain or loss of a proton. When a base accepts a proton, it forms its conjugate acid. Understanding this relationship is crucial for predicting the behavior of compounds in acid-base reactions and determining the stability of conjugate acids.

Resonance Stabilization

Resonance stabilization occurs when a molecule can be represented by two or more valid Lewis structures, which helps distribute charge across the molecule. This distribution can enhance the stability of the molecule, particularly in conjugate acids, by delocalizing positive charge. Recognizing resonance forms is essential for assessing the relative stability of different conjugate acids.

Acid Stability and Electronegativity

The stability of conjugate acids is influenced by the electronegativity of atoms involved and the ability to stabilize positive charge. More electronegative atoms can better stabilize positive charges, making the conjugate acid more stable. Additionally, the presence of electron-withdrawing groups can enhance stability by dispersing charge, which is key in ranking the stability of conjugate acids.

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Related Practice

Textbook Question

Ammonia appears in [TABLE 2-2] as both an acid and a conjugate base.

d. Show how methanol (CH₃OH) can serve as both an acid and a base. Write an equation for the reaction of methanol with sulfuric acid.

Textbook Question

The following compounds can all react as acids.

a. For each compound, show its conjugate base. Show any resonance forms if applicable.

Textbook Question

Oxidation of a primary alcohol to an aldehyde usually gives some over-oxidation to the carboxylic acid. Assume you have used PCC to oxidize pentan-1-ol to pentanal.

(a) Show how you would use acid–base extraction to purify the pentanal.

(b) Which of the expected impurities cannot be removed from pentanal by acid–base extractions? How would you remove this impurity?

Textbook Question

The boiling points of hex-1-ene (64 °C) and hex-1-yne (71 °C) are sufficiently close that it is difficult to achieve a clean separation by distillation. Show how you might use the acidity of hex-1-yne to remove the last trace of it from a sample of hex-1-ene.

Textbook Question

Predict the products of the following acid–base reactions.

(g) HCOOH + CH₃O^– ⇌

(h) ⁺NH₃CH₂COOH + 2 ^–OH ⇌

Textbook Question

Sulfuric acid is a very strong acid. Show how the following equation can be used to explain that sulfuric acid is at once an Arrhenius, Brønsted–Lowry, and Lewis acid.

Multiple Choice

Which of the following factors does not affect the acidity of a compound?

Multiple Choice

Which of the following is a characteristic of a strong acid in aqueous solution?

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