Chem 113 / Exam 1 Review

You add excess Sodium Acetate (NaCH₃COOH), Sodium Chloride (NaCl), and Sodium Iodide (NaI) to an aqueous solution of Silver Nitrate (AgNO₃). Which salt would you expect to form a precipitate?

• Sodium Nitrate (NaNO₃)

• Silver Chloride (AgCl)

• Silver Iodide (AgI)

• Silver Acetate (AgCH₃COOH)

Mg(OH)₂ is an insoluble alkali metal hydroxide salt with Ksp = 7 x 10^–12. How will the molar solubility of Mg(OH)₂ change if the pH of its aqueous mixture is lowered from pH = 7 (neutral) to pH = 5?

• No change/not dependent on pH

• The solubility will increase by a factor of 2

• The solubility will increase by a factor of 100

• The solubility will increase by a factor of 10,000

Copper (II) forms an insoluble salt with sulfide (CuS, Ksp = 8 x 10^–37) and a soluble complex with ammonia (Kf = 1.1 x 10¹²). Which of the following equilibrium constants accurately describes the solubility of CuCl in an aqueous solution of ammonia?

• K = Ksp * Kf

• K = Ksp / Kf

• K = Ksp + Kf

• K = Ksp – Kf

The balanced solubility equilibrium of CuS in aqueous ammonia is CuS(s) + 4 NH₃ (aq) ⇌ [Cu(NH₃)₄]²⁺(aq) + S^2–(aq). If the molar solubility of CuS is represented by S, what would the equilibrium expression be for the solubility in a 1 M solution of ammonia?

• K = S⁴ / (1 - 4S)

• K = S⁴ / (1 - S)

• K = S² / (1 - 4S)

• K = S² / (1 - S)

Balance the redox reaction:

a MnO₄^– + b H⁺ + c Ce³⁺ → d Ce⁴⁺ + e Mn²⁺ + f H₂O

• a = 1, b = 8, c = 1, d = 1, e = 1, f = 4

• a = 1, b = 4, c = 1, d = 1, e = 1, f = 1

• a = 1, b = 8, c = 3, d = 3, e = 1, f = 4

• a = 1, b = 8, c = 5, d = 5, e = 1, f = 4

A galvanic cell is made from an Mg/Mg(2+) (ΔE°_red = -2.375 V) and Ni/Ni(2+) (ΔE°_red = -0.23 V) half cells. Which is the anode and cathode of the cell?

• Mg anode, Ni cathode

• Mg and Ni both anodes

• Mg cathode, Ni anode

• Mg and Ni both cathodes

The galvanic cell has the redox reaction:

Ni²⁺ + Mg → Ni + Mg²⁺

If a current of 1 A passes through the wire for 10 s, how many atoms of Ni are deposited on the corresponding electrode?

(Q_electron = 1.60 x 10^–19 C)

• (1) (10) (1.60 x 10¹⁹) (2)

• (1) (10) (1.60 x 10¹⁹) (2) (6.02 x 10²³)

• (1) (10) (1.60 x 10¹⁹)^-1 (2)^-1

• (1) (10) (1.60 x 10¹⁹)^-1 (2)^-1 (6.02 x 10²³)

A galvanic cell carries out the reaction:

2 Ag _(s) + Cl_{2 (g)} → 2 Ag⁺ _(aq) + 2 Cl^– _(aq).

Which is the correct Nernst equation expression for the reaction?

• ΔE° = ΔE°cell - 0.0592 log ([Ag⁺]² [Cl^–]² / P_Cl2)

• ΔE° = ΔE°cell - 0.0592 log ([Ag⁺]² [Cl^–]²)

• ΔE° = ΔE°cell - 0.0296 log ([Ag⁺]² [Cl^–]² / P_Cl2)

• ΔE° = ΔE°cell - 0.0592 log ([Ag⁺] [Cl^–] / P_Cl2)

For a reaction, the activation energy is 8.314 kJ/mol and the rate constant is k = 10 s^-1 at 100 K. What is the rate constant at 300 K, given the combined Arrhenius equation at two temperatures:

ln(k₂/k₁) = - E_a / R (1/T₂ - 1/T₁). (R = 8.314 J /mol K)

• k = 0.013 s^-1

• k = 10. s^-1

• k = 78 s^-1

• k = 7800 s^-1

For a given reaction (2A + 2B → C), it was determined that doubling the concentration of reactant A caused the reaction rate to increase by a factor of four. Conversely, the concentration of reactant B had no impact on the rate. Provide a rate law for this reaction:

• rate = k [A] [B]

• rate = k [A]² [B]²

• rate = k [A]²

• rate = k [B]²