The K_a of acetic acid is 1.8 times 10^-5. a. What is the pK_a of acetic acid? b. What should be the pH of a solution of 1.0 mL of 0.1 M acetic acid and 1.0 ml. of 0.1 M sodium acetate and 48.0 mL H_2 O? Justify your answer. c. What should be the pH of a solution of 5.0 ml. of 0.1 M acetic acid and 5.0 ml. of 0.1 M sodium acetate and 40.0 mL H_2O? Justify your answer.