Final Exam, Spring 2000

1. Complete and balance the following reactions.

a. H₂SO₄(aq) + LiOH(aq) (Exam A)

H₂SO₄(aq) + KOH(aq) (Exam B)

H₂SO₄(aq) + RbOH(aq) (Exam C)

H₂SO₄(aq) + CsOH(aq) (Exam D)

b. CH₃NH₂(aq) + H₂O(l) (Exam A)

(CH₃)₂NH(aq) + H₂O(l) (Exam B)

(CH₃)₃N(aq) + H₂O(l) (Exam C)

(CH₃CH₂)₂NH(aq) + H₂O(l) (Exam D)

c. Fe²⁺(aq) + H₂O(l) (Exam A)

Co²⁺(aq) + H₂O(l) (Exam B)

Zn²⁺(aq) + H₂O(l) (Exam C)

Cu²⁺(aq) + H₂O(l) (Exam D)

d. Ag⁺(aq) + NH₃(aq) (Exam A)

Cd²⁺(aq) + NH₃(aq) (Exam B)

Cu²⁺(aq) + NH₃(aq) (Exam C)

Zn²⁺(aq) + NH₃(aq) (Exam D)

e. BaCl₂(aq) + Na₂CO₃(aq) (Exam A)

MgCl₂(aq) + Na₂CO₃(aq) (Exam B)

CaCl₂(aq) + Na₂CO₃(aq) (Exam C)

SrCl₂(aq) + Na₂CO₃(aq) (Exam D)

f. Ni(OH)₂(s) + H₃PO₄(aq)

g. NO₃^–(aq) + H₂O(l)

h. OCN^–(aq) + HClO₄(aq)

i. H₃PO₃(aq) + H₂O₂(aq) → H₃PO₄(aq)

j. ClO₂^–(aq) → ClO^–(aq) + ClO₄^–(aq) (pH > 7)

2. Give an example of a complete and balanced reaction that has an equilibrium constant labeled as

a. K_a

b. K_b

c. K_f

d. K_sp

3. Consider the reaction: S₂O₈^2–(aq) + I^–(aq) → SO₄^2–(aq) + I₃^–(aq)

a. Balance the reaction.

b. If the concentration of either reactant is doubled, the rate also doubles. Write the rate law.

4. Consider the following cells:

a. Mn(s) | Mn(OH)₂(s) || MnO₄^–(aq) | MnO₂(s) | OH^–(aq) | Pt(s).

Write the net balanced reaction.

b. Mn(s) | MnO₂(s) | OH^–(aq) || MnO₄^–(aq) | Mn(OH)₂(s) | Pt(s).

Write the net balanced reaction.

c. Which of the reactions in parts a and b is thermodynamically favored? Why?

5. 1.0 L of a 0.10 M solution of HCN solution is prepared at 25 °C.

a. What is the pH of the solution at 25 °C?

b. What is ΔG° for the acid-base reaction used in part a at 25 °C?

c. What is ΔG° for the acid-base reaction used in part a at 75 °C?

d. What is K_a for HCN at 75 °C?

e. What is the pH of the HCN solution at 75 °C?

6. Consider the cell Ag(s) | AgI(s) | I^–(aq) || Ag⁺(aq) | Ag(s) at 25 °C.

a. Write the oxidation half-reaction.

b. Write the reduction half-reaction.

c. Write the net reaction.

d. Find the standard cell potential.

e. Find K_sp for AgI.

f. What is the molar solubility of AgI at 25 °C?

7. Answer each of the following questions in 10 words or less.

a. Carbonic acid is a stronger acid than hydrogen carbonate ion. Why?

b. When the temperature is raised, the solubility of calcium hydroxide decreases. What is the sign of the enthalpy change for this reaction?

c. What is the effect of a catalyst on the activation energy of a reaction?

d. The solubility of barium hydroxide decreases at high pH. Why?

e. Is sodium acetate an acidic, basic, or neutral salt?

Answers