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10. An acetate buffer solution is prepared by combining 50. mL of 0.20 M acetic acid, HC,H,O,(aq), and 50. mL of 0.20 M sodium acetate, NaC,H,O,(aq). A 5.0 mL sample of 0.10 M NaOH(aq) is added to the buffer solution. Which of the following is a correct pairing of the acetate species present in greater concentration and of the pH of the solution after the NaOH(aq) is added? (The pk, of acetic acid is 4.7.) Acetate Species pH (A) HC5H10 (B) HC,H,O2 > 4.7 (C) CH,022 C,H,O, < 4.7 (D) > 4.7
141 12 10- 8 pH 6+ 4 2 0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 Volume of NaOH (mL) 38. Data collected during the titration of a 20.0 mL sample of a 0.10 M solution of a monoprotic acid with a solution of NaOH of unknown concentration are plotted in the graph above. Based on the data, which of the following are the approximate pK, of the acid and the molar concentration of the NaOH? рк, [NaOH) (A) 4.7 0.050 M (B 4.7 0.10 M 9.3 0.050 M 9.3 0.10M
K pka A4 HC,H,O3(aq) 8.3 x 10-4 CH_NH,+(aq) 2.3 x 10-11 10-11 all 37. The acid-dissociation constants of HC,H,O3(aq) and CH NH3(aq) are given in the table above. Which of the following mixtures is a buffer with a pH of approximately 3 ? IA) A mixture of 100. mL of 0.1 M CH3NH,CI and 50. mL of 0.1 M NaOH (B) A mixture of 100. mL of 0.1 M HC2H:03 and 50. mL of 0.1 M NaOH (C) A mixture of 100. mL of 0,1 M NaC,H30; and 100. mL of 0.1 M NaOH DrA mixture of 100. mL of 0.1 M CH_NH,CI and 100. mL of 0.1 M CH_NH, CAJ HC at