Free Printable Electrochemistry Review

1.

AlF₆ ^3– + 3 e^– → Al + 6 F^{– 1}

Which of the following occurs in the reaction?

a)

AlF₆^3– is reduced at the cathode.

b)

Al is oxidized at the anode.

c)

Aluminum is converted from the –3 oxidation state to the 0 oxidation state.

d)

Aluminum is converted from the –3 oxidation state to the 0 oxidation state.

2.

AlF₆ ^3– + 3 e^– → Al + 6 F^{– 1}

A steady current of 10 amperes is passed though an aluminum-production cell for 15 minutes. Which of the following is the correct expressions for calculating the number of grams of aluminum produced? (1 faraday = 96,500 coulombs)

a)

b)

c)

d)

3.

Fe²⁺ + 2e^– → Fe(s) E° = –0.44 volt

Ni²⁺ + 2e^– → Ni(s) E° = –0.23 volt

The standard reduction potentials for two half reactions are given above. The Nernst equation for a galvanic cell at 25°C in which Fe(s) reduces Ni²⁺ is the following.

E = E° – 0.03 log [Fe²⁺]/[Ni²⁺]

What is the equilibrium constant for the reaction below?

Fe(s) + Ni²⁺ → Fe²⁺ + Ni(s)

a)

1.9 × 10^–23

b)

7.6 × 10^–8

c)

3.6 × 10³

d)

1.3 × 10⁷

4.

Which of the following best represents a reaction in which the same reactant undergoes both oxidation and reduction?

a)

S₈(s) + 8 O₂(g) → 8 SO₂(g)

b)

H₂SeO₄(aq) + 2 Cl^–(aq) + 2 H⁺(aq) → H₂SeO₃(aq) + Cl₂(g) + H₂O(l)

c)

3 Br₂(aq) + 6 OH^–(aq) → 5 Br^– (aq) + BrO₃ ^– (aq) + 3 H₂O(l)

d)

PtCl₄(s) + 2 Cl^–(aq) → PtCl₆^2– (aq)

5.

A redox reaction has an equilibrium constant of

K = 2.6 x 10⁵. Which of the following statements best represents the algebraic signs of E^o_cell and G^o_rxn for this reaction?

a)

E^o_cell is positive and G^o_rxn is positive.

b)

E^o_cell is negative and G^o_rxn is negative.

c)

E^o_cell is positive and G^o_rxn is negative.

d)

E^o_cell is negative and G^o_rxn is positive.

6.

Which of the following statements applies to the change in mass of the electrodes involved in this electrochemical cell?

a)

Electrode A is the anode and it gains mass

since metal ions are being converted to metal

atoms which often adhere to the electrode.

b)

Electrode B is the anode and it gains mass

since metal ions are being converted to metal

atoms which often adhere to the electrode.

c)

Electrode A is the cathode and it gains mass since metal ions are being converted to metal atoms which often adhere to the electrode.

d)

Electrode B is the cathode and it gains mass since metal ions are

being converted to metal atoms which often adhere to the electrode.

7.

Which of the following best describes this electrochemical cell?

a)

Electrode A is the anode since anions are present in its half-cell and the current flows from cathode to anode.

b)

Electrode C is the cathode since cations are present in its half-cell and the current flows from anode to cathode.

c)

Electrode A is the anode and Electrode C is the cathode since the current always flows from cathode to anode.

d)

Electrode C is the anode and Electrode A is the cathode since the current always flows from anode to cathode.

8.

Which of the following best describes the function of the portion of the electrochemical cell labeled B?

a)

Structure B functions to complete the electrical circuit present in the electrolytic cell.

b)

Structure B provides soluble anions that migrate to the anode as well as soluble cations that migrate to the cathode, thus maintaining a balance of charge in the electrolytic cell.

c)

Structure B provides soluble anions that migrate to the anode as well as soluble cations that migrate to the cathode, thus maintaining a balance of charge in the galvanic cell.

d)

Structure B provides soluble anions that migrate to the cathode as well as soluble cations that migrate to the anode, thus maintaining a charge balance in the galvanic cell.

9.

A student wishes to construct a thermodynamically favorable galvanic cell using electrodes made of chromium and silver. Each half cell will consist of the electrode partially submerged in a 1.0 M solutions of its nitrate salt. The two electrodes will be connected by separate wires to a voltmeter and the two half-cells will be connected with a salt bridge.

Which of the following best represents the

initial reading on the voltmeter?

a)

–0.13 V

b)

–1.53 V

c)

1.53 V

d)

3.13 V

10.

A student wishes to construct a thermodynamically favorable galvanic cell using electrodes made of chromium and silver. Each half cell will consist of the electrode partially submerged in a 1.0 M solutions of its nitrate salt. The two electrodes will be connected by separate wires to a voltmeter and the two half-cells will be connected with a salt bridge.

Which metal serves as the anode in the student’s

thermodynamically favorable galvanic cell using electrodes

made of chromium and silver?

a)

Ag since reduction takes place in that half-cell.

b)

Ag since oxidation takes place in that half-cell.

c)

Cr since reduction takes place in that half-cell.

d)

Cr since oxidation takes place in that half-cell.

11.

A student wishes to construct a thermodynamically favorable galvanic cell using electrodes made of chromium and silver. Each half cell will consist of the electrode partially submerged in a 1.0 M solutions of its nitrate salt. The two electrodes will be connected by separate wires to a voltmeter and the two half-cells will be connected with a salt bridge.

The student constructs another galvanic cell still using

silver and chromium electrodes, but substitutes a 0.50 M

solution of silver nitrate for the 1.0 M solution of silver

nitrate in the silver half-cell. Which of the following best

describes the effect this substitution has on the initial reading on the voltmeter?

a)

The voltage will increase in both cells.

b)

The voltage will decrease in both cells.

c)

The voltage will increase due to fewer reactants being present.

d)

The voltage will decrease due to fewer reactants being present.

12.

An experiment was conducted in which two test tubes were filled with water at 25C and 1 atm pressure. Each test tube was subsequently inverted into a beaker containing water which was then acidified.

Which of the following best describes the reaction taking place in Test Tube A?

a)

E^o_cell is positive, G^o is positive

b)

E^o_cell is positive, G^o is negative

c)

E^o_cell is negative, G^o is positive

d)

E^o_cell is negative, G^o is negative

13.

An experiment was conducted in which two test tubes were filled with water at 25C and 1 atm pressure. Each test tube was subsequently inverted into a beaker containing water which was then acidified.

Which of the following best represents the half-reaction occurring at the anode?

a)

H₂O(l) → H₂(g) + O₂(g)

b)

2 H₂O(l) → 2 H₂(g) + O₂(g)

c)

2 H₂O(l) → O₂(g) + 4 H⁺(aq) + 4 e^–

d)

2 H₂O(l) + 2 e^– → H²(g) + 2 OH^–(aq)

14.

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?

a)

Pure copper anode & pure zinc cathode

b)

Pure zinc anode & pure copper cathode

c)

Pure copper anode & impure copper cathode

d)

Impure copper anode & pure copper cathode

15.

Which of the following occurs if a 50-milliliter sample of a 2-molar Cd(NO₃)₂ solution is added to the left beaker?

a)

Voltage increases.

b)

Voltage decreases.

c)

Voltage becomes zero and remains at zero.

d)

No change in voltage occurs.

Electrochemistry Review

Total questions: 15

Worksheet time: 25mins

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