Exam 3B, Spring 1999

1. Complete and balance the following reactions:

a. HCO₃^–(aq) + KOH(aq)

b. HPO₄^2–(aq) + H₂O(l)

c. Co(NO₃)₂(aq) + H₂O(l)

d. Cr(NO₃)₂(aq) + KOH(aq)

e. BaCl₂(aq) + H₂SO₄(aq)

f. CuNO₃(aq) + NaCN(aq)

2. On the titration curve shown, give estimates for the following: the pH at the equivalence point, the equivalence volume, and the pK_a.

3. Consider a 0.65 M solution of dimethylamine, (CH₃)₂NH, at 25 °C.

a. What is the pH of the solution?

b. What is the pH of the solution if enough dimethylammonium hydrobromide, (CH₃)₂NH₂Br , is added so that the dimethylammonium ion concentration becomes 0.65 M?

4. Consider copper(II) hydroxide at 25 °C.

a. What is the molar solubility in pure water?

b. What is the molar solubility in 1.0 M Cu(NO₃)₂ solution?

c. What is the molar solubility in 1.0 M NH₃ solution?

5. You are given 1.0 M solutions of sodium dihydrogen phosphate and sodium hydrogen phosphate. How many mL of each solution are required to prepare 100.0 mL of a buffer with pH = 7.40 at 25 °C.

Answers