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

Ranking Acidity

Organic Chemistry

3. Acids and Bases

Ranking Acidity

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5:39 minutes

Problem 51e

Textbook Question

Identify the most stable conjugate base in each pair. Tell which structural features you analyzed and why you weighted them as you did in picking one answer.
(e)

Verified step by step guidance

Analyze the conjugate bases in the given pair by identifying the acidic hydrogen that would be removed to form each conjugate base. Use the Bronsted-Lowry definition of acids and bases, where the conjugate base is formed by the loss of a proton (H⁺).

Examine the stability of each conjugate base by considering resonance effects. If the negative charge on the conjugate base can be delocalized through resonance, it will increase the stability of that base. Write out the resonance structures, if applicable, to visualize this delocalization.

Evaluate the inductive effects in each conjugate base. Electronegative atoms or groups near the negatively charged atom can stabilize the charge by withdrawing electron density through sigma bonds. Compare the extent of inductive stabilization in each structure.

Assess the hybridization of the atom bearing the negative charge in each conjugate base. A negative charge on an sp-hybridized atom is more stable than on an sp² or sp³ atom due to the increased s-character, which holds the charge closer to the nucleus.

Compare the overall stability of the conjugate bases based on the factors above (resonance, inductive effects, and hybridization). The conjugate base with the most stabilizing features will be the most stable. Clearly state which structural features were most influential in your decision and why.

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Key Concepts

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

Conjugate Bases

A conjugate base is the species that remains after an acid donates a proton (H+). The stability of a conjugate base is crucial in determining the strength of its corresponding acid; stronger acids have more stable conjugate bases. Factors influencing stability include electronegativity, resonance, and the size of the atom bearing the negative charge.

Resonance Stabilization

Resonance stabilization occurs when a negative charge can be delocalized over multiple atoms through resonance structures. This delocalization lowers the energy of the conjugate base, making it more stable. When comparing conjugate bases, those that can participate in resonance are generally more stable than those that cannot.

Electronegativity and Charge Distribution

Electronegativity refers to the ability of an atom to attract electrons. In the context of conjugate bases, a more electronegative atom stabilizes a negative charge better than a less electronegative one. When analyzing conjugate bases, the distribution of charge relative to electronegativity helps determine which base is more stable, as negative charges are more stable on electronegative atoms.

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Related Practice

Textbook Question

Which acid in each pair would you expect to more readily donate a proton to a basic compound?

(b)

Textbook Question

Using qualitative reasoning for the acid–base reactions shown,

(i) which is stronger, the acid or the conjugate acid?

(ii) Which side of the reaction is favored?

(iii) Would you expect a K_eq greater than, equal to, or less than 1?

(a)

Textbook Question

Using qualitative reasoning for the acid–base reactions shown,

(i) which is stronger, the base or the conjugate base?

(ii) Which side of the reaction is favored?

(iii) Would you expect a K_eq greater than or less than 1?

(a)

Textbook Question

Identify the most stable conjugate base in each pair. Tell which structural features you analyzed and why you weighted them as you did in picking one answer.

(c)

Textbook Question

Identify the most acidic proton in each pair. Tell which structural features you analyzed and why you weighted them as you did in picking one answer. [Always start by drawing the conjugate base.]

(a)

Textbook Question

Identify the most acidic proton in each pair. Tell which structural features you analyzed and why you weighted them as you did in picking one answer. [Always start by drawing the conjugate base.]

(h)

Textbook Question

Which anion in each pair would you expect to react more quickly with H⁺?

(a)

Textbook Question

Which anion in each pair would you expect to react more quickly with H⁺?

(b)

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