Problem Set 7: Acids and Bases-II
1) For a solution that is 0.275 M HC3H5O2 (propionic acid, Ka= 1.3*10-5) and 0.0892 M HI,
calculate (a) [H3O+]; (b) [OH-]; (c) [C3H5O2-]; (d) [I-].
2) For a solution that is 0.164 M NH3 and 0.102 M NH4Cl, calculate
(a) [OH-]; (b) [NH4+]; (c) [Cl-]; (d) [H3O+].
3) Calculate [H3O+] in a solution that is 0.100 M NaNO2 and 0.0550 M HNO2.
4) Calculate [OH-] in a solution that is 0.315 M (NH4)2SO4 and 0.486 M NH3.
5) Lactic acid, HC3H5O3, is found in sour milk. A solution containing 1.00 g NaC3H5O3 in 100.0
mL of 0.0500 M HC3H5O3 has a pH = 4.11. What is Ka of lactic acid?
6) What is the pH of a solution obtained by adding 1.15 mg of aniline hydrochloride
(C6H5NH3+Cl-) to 3.18 L of 0.105 M aniline (C6H5NH2)?
7) You wish to prepare a buffer solution with pH = 9.45.
(a) How many grams of (NH4)2SO4 would you add to 425 mL of 0.258 M NH3 to do this?
Assume that the solution’s volume remains constant.
(b) Which buffer component, and how much (in grams), would you add to 0.100 L of
the buffer in part (a) to change its pH to 9.30? Assume that the solution’s volume
remains constant.
8) A solution of volume 75.0 mL contains 15.5 mmol HCHO2 and 8.5 mmol NaCHO2.
(a) What is the pH of this solution?
(b) If 0.25 mmol Ba(OH)2 is added to the solution what will be the pH?
(c) If 1.05 mL of 12 M HCl is added to the original solution, what will be the pH?
9) Two aqueous solutions are mixed: 100.0 mL of HCl (aq) with pH 2.50 and 100.0 mL of
NaOH (aq) with pH 11.00. What is the pH of the resulting solution?
10) Determine the following characteristics of the titration curve for 20.0 mL of 0.275 M NH 3
(aq) titrated with 0.325 M HI (aq).
(a) the initial pH
(b) the volume of 0.325 M HI (aq) at the equivalence point
(c) the pH at the half-neutralization point
(d) the pH at the equivalence point
11) Is a solution that is 0.10 M Na2S (aq) likely to be acidic, basic, or pH neutral? Explain.