7. The ionization constant for arsenous acid (HAsO₂) is 6.0 x 10^-10. What is the PH of a 0.10-molar solution of arsenous acid? What is the pH of a 0.10-molar solution of NaAsO₂?

8. A solution of ammonia has a hydrogen ion concentration of 8.0 x10^-9 mole per liter. What is the pOH of this solution?

9. What is the CN^- ion concentration and the pOH in a 1.00-molar aqueous solution of HCN?

10. Pyridine is an organic base that reacts with water as follows:

C₅H₅N + H₂O = C₅H₅NH⁺ + OH^-

The base-dissociation constant for this reaction, K_b, is 1.58 x 10^-8. What is the concentration of C₅H₅NH⁺ ion in a solution that was initially 0.10 molar in pyridine? What is the pH of the solution?

11. What is the equilibrium concentration of NO₂^- ion in a 0.22-molar aqueous solution of nitrous acid? What is the pH? What is the percent ionization of HNO₂?

12. Hydrazine is a weak base that dissociates in water according to the equation

N₂H₄ + H₂O = N₂H₅⁺ + OH^-

The equilibrium constant for this dissociation at 25'C is 2.0 X 10^-6. Write the equilibrium-constant expression for this reaction. If the initial hydrazine concentration is 0.010 molar, what is the concentration of hydrazinium ion, N₂H₅⁺ ? What is the pH?

13. What is the pH of a 0.18-molar solution of ammonium chloride?

14. What is the pH of a 0.025-molar solution of sodium acetate?

15. What is the pH of a 1.0-molar solution of sodium cyanide?

16. A buffer solution is made with 0.30-molar sodium cyanide and 0.30-molar HCN. What is the pH of the buffer solution?

17. What is the pH of a buffer prepared to be 0.20 molar in NH₃ and 0.40 molar in NH₄Cl?

18. A buffer solution is made from equal volumes of 0.10-molar acetic acid and 0.10-molar sodium acetate. What is the pH of the buffer?