SOLVED

11) What is the pH of a buffer solution that is 0.222 M in lactic acid and 0.132 M in sodium lactate? The Ka of lactic acid is 1.4 × 10-4. A) 14.23 B) 10.38 C) 5.39 D) 3.62 E) 4.08 12) What is the pH of a buffer solution that is 0.255 M in hypochlorous acid (HClO) and 0.333 M in sodium hypochlorite? The Ka of hypochlorous acid is 3.8 × 10-8. A) 13.88 B) 6.46 C) 8.49 D) 7.30 E) 7.54 13) What is the pH of a solution prepared by mixing 25.00 mL of 0.10 M CH3CO2H with 25.00 mL of 0.040 M CH3CO2Na? Assume that the volume of the solutions are additive and that Ka = 1.8 × 10-5 for CH3CO2H. A) 2.87 B) 4.35 C) 4.75 D) 5.14 14) What is the pH of a solution prepared by mixing 50.00 mL of 0.10 M NH3 with 10.00 mL of 0.10 M NH4Cl? Assume that the volume of the solutions are additive and that Kb = 1.8 × 10-5 for NH3. A) 8.56 B) 9.28 C) 9.95 D) 11.13 15) What is the pH of a solution prepared by mixing 50.00 mL of 0.10 M methylamine, CH3NH2, with 15.00 mL of 0.10 M methylammonium chloride, CH3NH3Cl? Assume that the volume of the solutions are additive and that Kb = 3.70 × 10-4 for methylamine. A) 10.04 B) 10.57 C) 11.09 D) 11.78 16) What is the pH of a buffer system prepared by dissolving 10.70 grams of NH4Cl and 35.00 mL of 12 M NH3 in enough water to make 1.000 L of solution? Kb = 1.80 × 10-5 for NH3. A) 8.93 B) 9.26 C) 9.58 D) 11.32 17) What is the pH of a solution prepared by mixing 100.00 mL of 0.020 M Ca(OH)2 with 50.00 mL of 0.100 M NaOH? Assume that the volumes are additive. A) 12.67 B) 12.78 C) 12.95 D) 13.25 18) What is the hydronium ion concentration in a solution prepared by mixing 50.00 mL of 0.10 M HCN with 50.00 mL of NaCN? Assume that the volumes of the solutions are additive and that Ka = A) 2.0 × 10-10 M B) 4.9 × 10-10 M C) 1.2 × 10-9 M D) 7.0 × 10-6 M 19) What is the [CH3CO2-]/[CH3CO2H] ratio necessary to make a buffer solution with a pH of 4.44? Ka = 1.8 × 10-5 for CH3CO2H. 20) You wish to prepare an HC2H3O2 buffer with a pH of 4.14. If the pKa of is 4.74, what ratio of C2H3O2?/HC2H3O2 must you use? A) 0.10 B) 0.60 C) 0.25 D) 3.98 E) 4.0