Table of contents

1. Intro to General Chemistry3h 48m
2. Atoms & Elements4h 16m
3. Chemical Reactions4h 10m
4. BONUS: Lab Techniques and Procedures1h 38m
5. BONUS: Mathematical Operations and Functions48m
6. Chemical Quantities & Aqueous Reactions3h 53m
7. Gases3h 49m
8. Thermochemistry2h 37m
9. Quantum Mechanics2h 58m
10. Periodic Properties of the Elements3h 9m
11. Bonding & Molecular Structure3h 29m
12. Molecular Shapes & Valence Bond Theory1h 57m
13. Liquids, Solids & Intermolecular Forces2h 23m
14. Solutions3h 1m
15. Chemical Kinetics2h 53m
16. Chemical Equilibrium2h 29m
17. Acid and Base Equilibrium5h 1m
18. Aqueous Equilibrium4h 47m
19. Chemical Thermodynamics1h 50m
20. Electrochemistry2h 42m
21. Nuclear Chemistry2h 36m
22. Organic Chemistry5h 7m
23. Chemistry of the Nonmetals2h 39m
24. Transition Metals and Coordination Compounds3h 16m

17. Acid and Base Equilibrium

pH of Weak Bases

General Chemistry

17. Acid and Base Equilibrium

pH of Weak Bases

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Multiple Choice

What is the expression for the equilibrium constant (Kb) for the dissociation of a weak base in water?

Kb = [BH+][H2O] / [B][OH-]

Kb = [B][OH-] / [BH+]

Kb = [BH+][OH-] / [B]

Kb = [B][H2O] / [BH+][OH-]

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Verified step by step guidance

Identify the general reaction for the dissociation of a weak base (B) in water: B + H2O ⇌ BH+ + OH-. This reaction shows the base (B) accepting a proton from water to form its conjugate acid (BH+) and hydroxide ions (OH-).

Understand that the equilibrium constant for a base dissociation, Kb, is defined in terms of the concentrations of the products and reactants at equilibrium.

Write the expression for the equilibrium constant (Kb) based on the reaction: Kb = ([BH+][OH-]) / [B]. This expression is derived from the law of mass action, which states that the equilibrium constant is the ratio of the product of the concentrations of the products to the product of the concentrations of the reactants, each raised to the power of their stoichiometric coefficients.

Note that water (H2O) is a pure liquid and its concentration is not included in the equilibrium expression. In equilibrium expressions, the concentrations of pure solids and liquids are omitted because they are constant.

Verify that the correct expression for Kb is Kb = ([BH+][OH-]) / [B], which matches the given correct answer. This confirms that the expression accounts for the concentrations of the ions formed and the initial base.