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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5:21 minutes

Problem 81a,b

Textbook Question

Which species in each of the pairs in Problem 80 is the stronger base?
a.
b.

Verified step by step guidance

Step 1: Analyze the chemical structures in pair A. The species (i) is the formate ion (HCOO⁻), and species (ii) is the acetate ion (CH₃COO⁻). The difference lies in the substituent attached to the carboxylate group: hydrogen in (i) and a methyl group in (ii).

Step 2: Consider the inductive effect of the substituents. The methyl group in acetate (ii) is electron-donating, which stabilizes the negative charge on the oxygen atom through hyperconjugation and inductive effects. This stabilization reduces the basicity of acetate compared to formate.

Step 3: Conclude that formate (i) is the stronger base in pair A because it lacks the electron-donating methyl group, making the negative charge on the oxygen less stabilized and more available to accept a proton.

Step 4: Analyze the chemical structures in pair B. Both species are enolate ions, but the difference lies in the position of the negative charge. In species (i), the negative charge is on the carbon adjacent to the carbonyl group, while in species (ii), the negative charge is on the carbon further away from the carbonyl group.

Step 5: Consider resonance stabilization. In species (i), the negative charge is delocalized through resonance with the carbonyl group, making it more stable and less basic. In species (ii), the negative charge is less delocalized, making it less stable and more basic. Therefore, species (ii) is the stronger base in pair B.

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Key Concepts

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

Acidity and Basicity

Acidity refers to the ability of a species to donate a proton (H+), while basicity is the ability to accept a proton. In organic chemistry, the strength of an acid or base is often determined by the stability of its conjugate base or acid. A stronger base corresponds to a weaker acid, and vice versa, which is crucial for comparing the species in the given problem.

Resonance Stabilization

Resonance stabilization occurs when a molecule can be represented by two or more valid Lewis structures, leading to a delocalization of electrons. This delocalization can stabilize a negative charge in a conjugate base, making it less likely to accept a proton, thus affecting the basicity. Understanding resonance is essential for evaluating the strength of bases in the provided pairs.

Inductive Effect

The inductive effect refers to the electron-withdrawing or electron-donating effects of substituents on a molecule, which can influence acidity and basicity. Electronegative atoms or groups can stabilize a negative charge through their electron-withdrawing nature, while electron-donating groups can destabilize it. This concept is important for analyzing the structural differences in the pairs presented in the question.

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