CHM1 17 End-of-Chapter Problems Collection

1. In a solution of 2.4 X 10^-3 M HI, find the concentration of OH^-.
2. Determine the pH of a solution that is 0.0035 M HCl.
3. Determine the [H₃O⁺] of a solution with a pH = 5.65
4. If the pOH of NH₃, ammonia, in water is 4.74. What is the pH?  
5. Pepsin, a digestive enzyme in our stomach, has a pH of 1.5. Find the concentration of OH^- in the stomach. 
6. In a solution of acetic acid, the equilibrium concentrations are found to be [CH₃COOH] = 1.000; [CH₃COO^-] = 0.0042. Evaluate the pH of this solution and the equilibrium constant of ionization of acetic acid?
7. The acid-dissociation constant at 25.0°C for hypochlorous acid (HClO) is 3.0 × 10-8. At equilibrium, the molarity of H3O+ in a 0.010 M solution of HClO is ________.

   A) 1.7 × 10-5

   B) 0.010

   C) 5.8 × 10-10

   D) 4.76

   E) 2.00

8. What is the pH of a 0.30 M pyridine solution that has Kb = 1.9 × 10-9?  The equation for the dissociation of pyridine is

1. The value of Kb for methylamine, (CH3)₂NH, is 7.4 x 10–4. What is the pH of a solution containing 0.32 M dimethyl ammonium ion, (CH₃)₂NH₂⁺?

    

               (a) 5.68            (b) 6.58            (c) 8.32            (d) 5.43           (e) 4.34

10. Predict whether the pH of each of the following salts placed into water (forming an aqeuous solution, is acidic, basic, or neutral).

1. NaOCl_(s)
2. KCN_(s)
3. NH₄NO_3(s)

11. If additional OH^– is added to a sample of pure water, which of the following statements is incorrect? (a) The equilibrium position shifts to the left.

(b) The solution becomes more basic.

(c) The [H₃O⁺] remains unchanged.

(d) The [OH^–] > [H₃O⁺].

(e) The amount of non-ionized H₂O increases.

12. The pH of a solution is -0.38. What is the concentration of H3O+ ions in this solution?

13. Find the pH of a solution of .200 M NH₄NO₃. (K_a = 1.8 * 10^-5)

14. In a 2.0 M solution of acetic acid (CH₃COOH), calculate the [H⁺]. Use k_a= 1.8 x 10^-5

15. Calculate the pH of 0.030 M NH4Cl.

16. The pH of a 0.050 M solution of pyridine (C₆H₅N) is 8.96 at 25°C. Calculate K_b and pK_b for pyridine.

17. Calculate the pH and percent ionization of a 0.225 M solution of ethylamine (CH₃CH₂NH₂), which is used in the synthesis of some dyes and medicines. The pK_b of ethylamine is 3.19 at 20°C.

18. Use the information in the tables in this chapter to determine the pH of a solution prepared by dissolving 855 mg of sodium nitrite (NaNO₂) in enough water to make 100.0 mL of solution.

19. 

Arrange these acids in order of increasing strength.

• acid A: pK_a = 1.52
• acid B: pK_a = 6.93
• acid C: pK_a = 3.86

20. Calculate the K_a and the pK_a of the conjugate acid of a base with each pK_b value.

1. 
   
   1. 3.80
   2. 7.90
   3. 13.70
   4. 1.40
   5. ?2.50

21. Determine K_a and pK_a of boric acid [B(OH)₃], solutions of which are occasionally used as an eyewash; the pK_b of its conjugate base is 4.80.

22. 

Predict whether aqueous solutions of the following are acidic, basic, or neutral.

1. KI
2. Mg(ClO₄)₂
3. NaHS

Answers to End of Chapter Problems