AP Chem MC Section

2Ag⁺ + Cd(s) --> 2 Ag(s) + Cd²⁺

A 50-milliliter sample of a 2-molar Cd(NO₃)₂ solution is added to the left beaker.

• Voltage increases

• Voltage decreases

• Voltage becomes zero and remains zero

• No change in voltage

• Direction of voltage change cannot be predicted

2Ag⁺ + Cd(s) --> 2 Ag(s) + Cd²⁺

The silver electrode is made larger.

• Voltage increases

• Voltage decreases

• Voltage becomes zero and remains zero

• No change in voltage

• Direction of voltage change cannot be predicted

2Ag⁺ + Cd(s) --> 2 Ag(s) + Cd²⁺

The salt bridge is replaced by a platinum wire

• Voltage increases

• Voltage decreases

• Voltage becomes zero and remains zero

• No change in voltage

• Direction of voltage change cannot be predicted

2Ag⁺ + Cd(s) --> 2 Ag(s) + Cd²⁺

Current is allowed to flow for 5 minutes

• Voltage increases

• Voltage decreases

• Voltage becomes zero and remains zero

• No change in voltage

• Direction of voltage change cannot be predicted

In which of the follwing species does sulfur have the same oxidation number as it does in H₂SO₄?

• H₂SO₃

• S₂O₃^-2

• S₈

• SO₂Cl₂

When the equation for the half-reaction is balanced what is the ratio of the coefficients OH^-: CrO₂^-

• 1:1

• 2:1

• 3:1

• 4:1

If a copper sample containing some zinc impurity is to be purified by electrolysis, the anode and the cathode must be which of the following?

• Anode: Pure copper, Cathode: Pure zinc

• Anode: Pure zinc, Cathode: Pure copper

• Anode: Pure copper, Cathode: Impure copper

• Anode: Impure copper, Cathode: Pure copper

Zn(s) + Cu²⁺ à Zn²⁺ + Cu(s)

An electrolytic cell based on the reaction represented above was constructed from zinc and copper half-cells. The observed voltage was found to be 1.00 volt instead of the standard cell potential, E°, of 1.10 volts. Which of the following could correctly account for this observation?

• The copper electrode was larger than the zinc electrode.

• The Zn²⁺ electrolyte was Zn(NO₃)₂, while the Cu²⁺ electrolyte was CuSO₄.

• The Zn²⁺ solution was more concentrated than the Cu²⁺ solution.

• The solutions in the half-cells had different volumes.

• The salt bridge contained KCl as the electrolyte.

1. What is the maximum mass of copper that could be plated out by electrolyzing aqueous CuCl₂ for 16.0 hours at a constant current of 3.00 amperes? (1 faraday = 96,500 coulombs)

• 28 g

• 57 g

• 64 g

• 114 g

• 128 g

H₂Se (g) + 4 O₂F₂ (g) --> SeF₆ (g) + 2 HF (g) + 4 O₂ (g)

Which of the following is true regarding the reaction represented above?

• The oxidation number of O does not change.

• The oxidation number of H changes from -1 to +1.

• The oxidation number of F changes from +1 to -1.

• The oxidation number of Se changes from -2 to +6.

• It is a disproportionation reaction for F.