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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5:12 minutes

Problem 42g

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.
(g) KOH + CH₃CH₂OH ⇌

Verified step by step guidance

Step 1: Identify the acid and base in the reaction. Potassium hydroxide (KOH) is a strong base, and ethanol (CH3CH2OH) can act as a weak acid due to the presence of the hydroxyl (-OH) group.

Step 2: Write the reaction mechanism. KOH will deprotonate ethanol, resulting in the formation of CH3CH2O⁻ (ethoxide ion) and H2O (water). The reaction can be represented as: KOH + CH3CH2OH ⇌ K⁺ + CH3CH2O⁻ + H2O.

Step 3: Analyze the strength of the conjugate acid and base. Ethoxide ion (CH3CH2O⁻) is a strong conjugate base, and water (H2O) is a weak conjugate acid. This suggests that the equilibrium may favor the reactants.

Step 4: Consider the relative acidity of ethanol and water. Ethanol is a weaker acid compared to water, meaning the equilibrium will favor the side with the weaker acid, which is ethanol.

Step 5: Conclude the equilibrium direction. Based on the analysis, the equilibrium favors the reactants (KOH and CH3CH2OH) because the products include a strong base (CH3CH2O⁻) and a weak acid (H2O), which are less stable compared to the reactants.

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Key Concepts

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

Acid-Base Theory

Acid-base theory explains the behavior of acids and bases in chemical reactions. According to the Brønsted-Lowry theory, acids are proton donors and bases are proton acceptors. In the reaction between KOH and CH3CH2OH, KOH acts as a strong base, while CH3CH2OH (ethanol) can act as a weak acid, donating a proton.

Equilibrium in Chemical Reactions

Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products. The position of equilibrium can be influenced by factors such as concentration, temperature, and the strength of acids and bases involved. Understanding this concept is crucial for predicting whether the equilibrium favors reactants or products.

Strength of Acids and Bases

The strength of an acid or base is determined by its ability to donate or accept protons. Strong acids and bases dissociate completely in solution, while weak acids and bases do not. In the given reaction, KOH is a strong base, which will favor the formation of products, while ethanol is a weak acid, influencing the equilibrium position towards the products.

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Related Practice

Textbook Question

For each of the acid–base reactions in [Section 2.3], compare the pK_avalues of the acids on either side of the equilibrium arrows to prove that the equilibrium lies in the direction indicated.

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Textbook Question

Ethyne (HC≡CH) has a pK_a value of 25, water has a pK_a value of 15.7, and ammonia (NH3) has a pKa value of 36. Draw the equation, showing equilibrium arrows that indicate whether reactants or products are favored, for the acid–base reaction of ethyne with

a. HO^-.

Textbook Question

Given the data in Problem 47:

a. What pH would you make the water layer to cause the carboxylic acid to dissolve in the water layer and the amine to dissolve in the ether layer?

Textbook Question

Write equations for the following acid–base reactions. Label the conjugate acids and bases, and show any inductive stabilization. Predict whether the equilibrium favors the reactants or products. Try to do this without using a table of pKa values, but if you need a hint, you can consult Appendix 4.

j. CF₃CH₂O^– + FCH₂CH₂OH

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.

(f) (CH₃)₃C–O^– + H₂O ⇌

Textbook Question

Write equations for the following acid–base reactions. Label the conjugate acids and bases, and show any inductive stabilization. Predict whether the equilibrium favors the reactants or products. Try to do this without using a table of pK_a values, but if you need a hint, you can consult Appendix 4.

g. NaOCH₂CH₃ + Cl₂CHCH₂OH

h. H₂Se + NaNH₂

i. CH₃CHFCOOH + FCH₂CH₂COO^–

Textbook Question

For each of the following compounds (here shown in their acidic forms), write the form that predominates in a solution with a pH = 5.5:

c. H₃O⁺ (pK_a = −1.7)

d. HBr (pK_a = −9)

Textbook Question

Do the equilibria of the following acid–base reactions lie to the right or the left? (The pK_a of H2O2 is 11.6.)

HOOH + HO⁻⇌ HOO⁻+ H2O

RC☰CH + HOO⁻⇌ RC☰C⁻+ HOOH

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