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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2:56 minutes

Problem 4a

Textbook Question

Which is the most acidic compound in each pair?
(a)

Verified step by step guidance

Step 1: Understand the concept of acidity in organic compounds. Acidity is determined by the ability of a compound to donate a proton (H⁺). The more stable the conjugate base formed after losing a proton, the more acidic the compound.

Step 2: Analyze the functional groups present in the compounds. Functional groups like carboxylic acids (-COOH), phenols (-OH attached to an aromatic ring), and alcohols (-OH) have varying levels of acidity. Carboxylic acids are generally more acidic than phenols, which are more acidic than alcohols.

Step 3: Consider the effect of electronegativity and resonance stabilization. Electronegative atoms near the acidic proton can stabilize the conjugate base by withdrawing electron density. Resonance stabilization of the conjugate base also increases acidity.

Step 4: Evaluate inductive effects and hybridization. Electron-withdrawing groups (e.g., halogens) increase acidity by stabilizing the conjugate base through inductive effects. Additionally, sp-hybridized carbons are more acidic than sp² or sp³ due to increased s-character.

Step 5: Compare the two compounds in each pair based on the above factors. Determine which compound has the more stable conjugate base and thus is more acidic.

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Key Concepts

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

Acidity and pKa

Acidity in organic chemistry refers to the tendency of a compound to donate a proton (H+). The strength of an acid is often measured by its pKa value; lower pKa values indicate stronger acids. Understanding the relationship between structure and acidity is crucial, as factors like electronegativity and resonance can significantly influence a compound's ability to donate protons.

Resonance Stabilization

Resonance stabilization occurs when a molecule can be represented by multiple valid Lewis structures, allowing for the delocalization of electrons. This delocalization can stabilize the negative charge that results from deprotonation, making the compound more acidic. Recognizing resonance structures helps predict which compound in a pair is more likely to donate a proton.

Inductive Effect

The inductive effect refers to the electron-withdrawing or electron-donating influence of substituents on a molecule. Electronegative atoms or groups can stabilize the negative charge of a conjugate base through the inductive effect, enhancing acidity. Understanding how different substituents affect acidity through this mechanism is essential for comparing acidic strength in compounds.

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