Table of contents

Skip topic navigation

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

Previous problemNext problem

Struggling with General Chemistry?

Join thousands of students who trust us to help them ace their exams!Watch the first video

Multiple Choice

Calculate the pH of a 0.205 M KNO2 solution, given that the Ka of nitrous acid (HNO2) is 4.6 × 10^(-4).

7.00

5.92

8.08

9.14

Previous problemNext problem

Verified step by step guidance

Identify that KNO2 is a salt derived from a weak acid (HNO2) and a strong base (KOH). Therefore, the solution will be basic due to the hydrolysis of the NO2- ion.

Write the hydrolysis equation for the NO2- ion: NO2^- + H2O ⇌ HNO2 + OH^-. This shows that NO2- reacts with water to form HNO2 and OH^-.

Use the relationship between Ka and Kb to find the Kb for NO2-. The formula is Kb = Kw / Ka, where Kw is the ion-product constant of water (1.0 × 10^(-14) at 25°C).

Set up the expression for Kb: Kb = [HNO2][OH^-] / [NO2^-]. Assume that the change in concentration of NO2- due to hydrolysis is small, so [NO2^-] ≈ 0.205 M.

Solve for [OH^-] using the Kb expression, then calculate the pOH of the solution. Finally, use the relationship pH + pOH = 14 to find the pH of the solution.