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

Acid Base Equilibrium

Organic Chemistry

3. Acids and Bases

Acid Base Equilibrium

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1:56 minutes

Problem 28

Textbook Question

Given the following K_eq values, how much stronger of an acid is methanol (CH₃OH) than acetylene (HC≡CH)?

Verified step by step guidance

Identify the equilibrium constant (K_eq) values for methanol (CH₃OH) and acetylene (HC≡CH). These values are typically related to the acid dissociation constants (K_a) of the acids.

Recall that the strength of an acid is directly proportional to its K_a value. A higher K_a indicates a stronger acid.

To compare the acid strengths, calculate the ratio of the K_a values of methanol to acetylene. This can be expressed as:

\frac{K_{a}}{(} / K_{a} (HC \equiv CH)

Take the logarithm (base 10) of the ratio to express the difference in acid strength in terms of pKa values. Recall that

pK a = - \log (K_{a})

Interpret the result: A difference of 1 in pKa corresponds to a 10-fold difference in acid strength. Use this relationship to determine how much stronger methanol is as an acid compared to acetylene.

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Key Concepts

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

Acid-Base Strength

Acid-base strength is determined by the ability of an acid to donate protons (H⁺) in a solution. Stronger acids have a greater tendency to dissociate and release protons, leading to higher concentrations of H⁺ ions. The strength of an acid can be quantitatively expressed using the acid dissociation constant (K_a), where a larger K_a indicates a stronger acid.

Equilibrium Constant (K_eq)

The equilibrium constant (K_eq) is a numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium for a given reaction. In acid-base reactions, K_eq can be used to compare the strengths of different acids. A higher K_eq value for an acid indicates that it is more likely to donate protons compared to another acid, thus being stronger.

Comparative Acid Strength

To compare the strength of two acids, one can use the relationship between their K_a values or K_eq values. The difference in their K_eq values can be used to calculate how many times stronger one acid is compared to another. This comparison is essential in organic chemistry to predict the behavior of acids in various chemical reactions and their reactivity.

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Related Practice

Textbook Question

Given the value of K_eq for the following acid–base reactions, identify the weakest acid and the weakest base.

(c)

Textbook Question

Given the value of K_eq for the following acid–base reactions, identify the weakest acid and the weakest base.

(b)

Textbook Question

Given the value of K_eq for the following acid–base reactions, identify the weakest acid and the weakest base.

(a)

Textbook Question

Given the K_eq values for the following acid–base reactions, identify the strongest acid and the strongest base.

(c)

Textbook Question

Given the following K_eq values, how much stronger of a base is acetate (CH₃CO₂^-) than chloride (Cl⁻)?

Textbook Question

Explain why an amide ion cannot be used to form a carbanion from an alkane in a reaction that favors products.

Textbook Question

Predict the products of the following acid–base reactions, or indicate if no significant reaction would take place.

a. H—C≡C—H + NaNH₂

b. H—C≡C—H + CH₃Li

c. H—C≡C—H + NaOCH₃

Textbook Question

Complete the following acid–base reactions. In each case, indicate whether the equilibrium favors the reactants or the products, and explain your reasoning.

(e) (CH₃)₃C–O^– + CH₃CH₂OH ⇌

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Given the following Keq values, how much stronger of an acid is methanol (CH3OH) than acetylene (HC≡CH)?

Key Concepts

Acid-Base Strength

Equilibrium Constant (K_eq)

Comparative Acid Strength

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Given the following K_eq values, how much stronger of an acid is methanol (CH₃OH) than acetylene (HC≡CH)?