Exam 3B, Spring 2018

1. Complete and balance the following in aqueous solution.

a. cyanate ion plus perchloric acid

b. NH₃(aq) + HClO₂(aq)

c. Zn(NO₃)₂(aq) + Cs₂S(aq)

d. CdC₂O₄(s) + HNO₃(aq)

e. Co²⁺(aq) + H₂O(l)

f. Ni²⁺(aq) + NH₃(aq)

2. Which is the stronger acid, AsH₃ or PH₃? Provide a brief explanation.

3. Is a solution of Na₃PO₄ acidic, basic, or neutral? Show reactions that support your conclusion.

4. A solution is prepared with [NH₃] = 0.050 M and [NH₄⁺] = 0.010 M. Find the pH.

5. Consider ZnCO₃:

a. Find the molar solubility of ZnCO₃ in water at 25 °C. K_sp = 1.4×10^–11

b. Find the molar solubility of ZnCO₃ in a 0.10 M solution of NH₃ at 25 °C. Assume that the ammonia concentration does not change significantly. Is the assumption valid? Why or why not?

Answers