Question 1

Which of the following solids is commonly used as an inactive electrode in electrochemical cells?

Accepted Answer

A) Zinc 
B) Graphite 
C) Copper 
D) Iron 
E) Sodium 
A) Zinc 
B) Graphite 
C) Copper 
D) Iron 
E) Sodium

Question 2

A voltaic cell consists of a Ag/Ag+ electrode (E° = 0.80 V) and a Fe2+/Fe3+ electrode (E° = 0.77 V) with the following initial molar concentrations: [Fe2+] = 0.30 M; [Fe3+] = 0.10 M; [Ag+] = 0.30 M. What is the equilibrium concentration of Fe3+? (Assume the anode and cathode solutions are of equal volume, and a temperature of 25°C.)

Accepted Answer

A) 0.030 M 
B) 0.043 M 
C) 0.085 M 
D) 0.11 M 
E) 0.17 M 
A) 0.030 M 
B) 0.043 M 
C) 0.085 M 
D) 0.11 M 
E) 0.17 M

Question 3

A voltaic cell prepared using aluminum and nickel has the following cell notation. Al(s) | Al3+(aq) || Ni2+(aq) | Ni(s)
Which of the following represents the correctly balanced spontaneous reaction equation for the cell?

Accepted Answer

A) Ni 2+( aq)+ Al( s)→ Al 3+( aq)+ Ni( s) 
B) 3Ni 2+( aq)+ 2Al( s)→ 2Al 3+( aq)+ 3Ni( s) 
C) Ni( s)+ Al 3+( aq)→ Ni 2+( aq)+ Al( s) 
D) 3Ni( s)+ 2Al 3+( aq)→ 3Ni 2+( aq)+ 2Al( s) 
E) None of these choices are correct. 
A) Ni 2+( aq)+ Al( s)→ Al 3+( aq)+ Ni( s) 
B) 3Ni 2+( aq)+ 2Al( s)→ 2Al 3+( aq)+ 3Ni( s) 
C) Ni( s)+ Al 3+( aq)→ Ni 2+( aq)+ Al( s) 
D) 3Ni( s)+ 2Al 3+( aq)→ 3Ni 2+( aq)+ 2Al( s) 
E) None of these choices are correct.

Question 4

A battery that cannot be recharged is a

Accepted Answer

A) fuel cell. 
B) primary battery. 
C) secondary battery. 
D) simple battery. 
E) flow battery. 
A) fuel cell. 
B) primary battery. 
C) secondary battery. 
D) simple battery. 
E) flow battery.

Question 5

Chromium metal is electroplated from acidic aqueous solutions containing the dichromate ion, Cr2O72-. What is the minimum time needed to plate out 10.0 g of chromium metal from such a solution, if the current is 50.0 A?

Accepted Answer

A) 6.2 minutes 
B) 12.4 minutes 
C) 18.6 minutes 
D) 24.7 minutes 
E) 37.1 minutes 
A) 6.2 minutes 
B) 12.4 minutes 
C) 18.6 minutes 
D) 24.7 minutes 
E) 37.1 minutes

Question 6

Which one of the following statements about electrochemical cells is correct?

Accepted Answer

A) In a salt bridge, current is carried by cations moving toward the anode, and anions toward the cathode. 
B) In the external wire, electrons travel from cathode to anode. 
C) The anode of a voltaic cell is labeled minus (−). 
D) Oxidation occurs at the cathode, in an electrolytic cell. 
E) None of these choices are correct. 
A) In a salt bridge, current is carried by cations moving toward the anode, and anions toward the cathode. 
B) In the external wire, electrons travel from cathode to anode. 
C) The anode of a voltaic cell is labeled minus (−). 
D) Oxidation occurs at the cathode, in an electrolytic cell. 
E) None of these choices are correct.

Question 7

What is the E°cell for the cell represented by the combination of the following half-reactions? 2Hg2+(aq) + 2e- ⇄ Hg22+(aq) E° = 0.92 V
Cr3+(aq) + 3e- ⇄ Cr(s) E° = -0.74 V

Accepted Answer

A) -0.18 V 
B) 0.18 V 
C) 1.28 V 
D) 1.66 V 
E) 2.12 V 
A) -0.18 V 
B) 0.18 V 
C) 1.28 V 
D) 1.66 V 
E) 2.12 V

Question 8

A voltaic cell prepared using zinc and iodine has the following cell notation. Zn(s) | Zn2+(aq) || I−(aq) | I2(s) | C(graphite)
Which of the following equations correctly represents the balanced, spontaneous, cell reaction?

Accepted Answer

A) 2I −( aq)+ Zn 2+( aq)→ I 2( s)+ Zn( s) 
B) I 2( s)+ Zn( s)→ 2I −( aq)+ Zn 2+( aq) 
C) 2I −( aq)+ Zn( s)→ I 2( s)+ Zn 2+( aq) 
D) I 2( s)+ Zn 2+( aq)→ 2I −( aq)+ Zn( s) 
E) None of these choices are correct. 
A) 2I −( aq)+ Zn 2+( aq)→ I 2( s)+ Zn( s) 
B) I 2( s)+ Zn( s)→ 2I −( aq)+ Zn 2+( aq) 
C) 2I −( aq)+ Zn( s)→ I 2( s)+ Zn 2+( aq) 
D) I 2( s)+ Zn 2+( aq)→ 2I −( aq)+ Zn( s) 
E) None of these choices are correct.

Question 9

Given that E° for X + e- → Y is greater than E° for A + 2e- → B, it is correct to say that, under standard conditions

Accepted Answer

A) X will oxidize A. 
B) Y will oxidize A. 
C) Y will reduce A. 
D) B will oxidize X. 
E) B will reduce X. 
A) X will oxidize A. 
B) Y will oxidize A. 
C) Y will reduce A. 
D) B will oxidize X. 
E) B will reduce X.

Question 10

Calculate ΔG° for the oxidation of 3 moles of copper by nitric acid. Cu2+(aq) + 2e− ⇄ Cu(s) E° = 0.34 V
NO3−(aq) + 4H+(aq) + 3e− ⇄ NO(g) + 2H2O(l) E° = 0.957 V

Accepted Answer

A) −120 kJ 
B) −180 kJ 
C) −240 kJ 
D) −300 kJ 
E) −360 kJ 
A) −120 kJ 
B) −180 kJ 
C) −240 kJ 
D) −300 kJ 
E) −360 kJ

Question 11

Which one of the following statements relating to the glass electrode is correct?

Accepted Answer

A) The glass electrode detects hydrogen gas. 
B) The glass of a glass electrode serves to conduct electrons. 
C) When pH is measured, only a single electrode, the glass electrode, need be used. 
D) The potential of the glass electrode varies linearly with the pH of the solution. 
E) None of these choices are correct. 
A) The glass electrode detects hydrogen gas. 
B) The glass of a glass electrode serves to conduct electrons. 
C) When pH is measured, only a single electrode, the glass electrode, need be used. 
D) The potential of the glass electrode varies linearly with the pH of the solution. 
E) None of these choices are correct.

Question 12

Which of the following elements can be isolated by electrolysis of the aqueous salt shown?

Accepted Answer

A) Phosphorus from K 3PO 4( aq) 
B) Sodium from NaBr( aq) 
C) Aluminum from AlCl 3( aq) 
D) Fluorine from KF( aq) 
E) Iodine from NaI( aq) 
A) Phosphorus from K 3PO 4( aq) 
B) Sodium from NaBr( aq) 
C) Aluminum from AlCl 3( aq) 
D) Fluorine from KF( aq) 
E) Iodine from NaI( aq)

Question 13

Which of the following statements about voltaic and electrolytic cells is correct?

Accepted Answer

A) The electrons in the external wire flow from cathode to anode in both types of cell. 
B) Oxidation occurs at the cathode only in a voltaic cell. 
C) The free energy change, Δ G, is negative for an electrolytic cell. 
D) The cathode is labeled as positive (+)in a voltaic cell but negative (-)in an electrolytic cell. 
E) Reduction occurs at the anode in an electrolytic cell. 
A) The electrons in the external wire flow from cathode to anode in both types of cell. 
B) Oxidation occurs at the cathode only in a voltaic cell. 
C) The free energy change, Δ G, is negative for an electrolytic cell. 
D) The cathode is labeled as positive (+)in a voltaic cell but negative (-)in an electrolytic cell. 
E) Reduction occurs at the anode in an electrolytic cell.

Question 14

Electrolytic cells utilize electrical energy to drive nonspontaneous redox reactions.

Accepted Answer

A) True 
 B)False

Question 15

A salt bridge provides a path for electrons to move between the anode and cathode compartments of a voltaic cell.

Accepted Answer

A) True 
 B)False

Question 16

What mass of silver will be formed when 15.0 A are passed through molten AgCl for 25.0 minutes?

Accepted Answer

A) 0.419 g 
B) 6.29 g 
C) 12.6 g 
D) 25.2 g 
E) 33.4 g 
A) 0.419 g 
B) 6.29 g 
C) 12.6 g 
D) 25.2 g 
E) 33.4 g

Question 17

Examine the following half-reactions and select the strongest oxidizing agent among the substances. [PtCl4]2−(aq) + 2e− ⇄ Pt(s) + 4Cl−(aq) E° = 0.755 V
RuO4(s) + 8H+(aq) + 8e− ⇄ Ru(s) + 4H2O(l) E° = 1.038 V
FeO42−(aq) + 8H+(aq) + 3e− ⇄ Fe3+(aq) + 4H2O(l) E° = 2.07 V
H4XeO6(aq) + 2H+(aq) + 2e− ⇄ XeO3(aq) + 3H2O(l) E° = 2.42 V

Accepted Answer

A) [PtCl 4] 2-( aq) 
B) RuO 4( s) 
C) HFeO 4− ( aq) 
D) H 4X eO 6( aq) 
E) Cl −( aq) 
A) [PtCl 4] 2-( aq) 
B) RuO 4( s) 
C) HFeO 4− ( aq) 
D) H 4X eO 6( aq) 
E) Cl −( aq)

Question 18

What mass of copper will be deposited when 18.2 A are passed through a CuSO4 solution for 45.0 minutes?

Accepted Answer

A) 16.2 g 
B) 33.4 g 
C) 40.6 g 
D) 81.3 g 
E) 163 g 
A) 16.2 g 
B) 33.4 g 
C) 40.6 g 
D) 81.3 g 
E) 163 g

Question 19

Calculate E°cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. Co3+(aq) + e− ⇄ Co2+(aq) E° = 1.82 V
MnO4−(aq) + 2H2O(l) + 3e- ⇄ MnO2(s) + 4OH−(aq) E° = 0.59 V
Overall reaction:
MnO4−(aq) + 2H2O(l) + 3Co2+(aq) → MnO2(s) + 3Co3+(aq) + 4OH−(aq)

Accepted Answer

A) E° cell = -1.23 V, spontaneous 
B) E° cell = -1.23 V, nonspontaneous 
C) E° cell = 1.23 V, spontaneous 
D) E° cell = 1.23 V, nonspontaneous 
E) E° cell = -0.05 V, nonspontaneous 
A) E° cell = -1.23 V, spontaneous 
B) E° cell = -1.23 V, nonspontaneous 
C) E° cell = 1.23 V, spontaneous 
D) E° cell = 1.23 V, nonspontaneous 
E) E° cell = -0.05 V, nonspontaneous

Question 20

A secondary cell (battery) can operate either as a galvanic or an electrolytic cell.

Accepted Answer

A) True 
 B)False

Exam 21: Electrochemistry: Chemical Change and Electrical Work

Which of the following solids is commonly used as an inactive electrode in electrochemical cells?

A voltaic cell prepared using aluminum and nickel has the following cell notation. Al(s) | Al3+(aq) || Ni2+(aq) | Ni(s) Which of the following represents the correctly balanced spontaneous reaction equation for the cell?

A battery that cannot be recharged is a

Chromium metal is electroplated from acidic aqueous solutions containing the dichromate ion, Cr2O72-. What is the minimum time needed to plate out 10.0 g of chromium metal from such a solution, if the current is 50.0 A?

Which one of the following statements about electrochemical cells is correct?

What is the E°cell for the cell represented by the combination of the following half-reactions? 2Hg2+(aq) + 2e- ⇄ Hg22+(aq) E° = 0.92 V Cr3+(aq) + 3e- ⇄ Cr(s) E° = -0.74 V

A voltaic cell prepared using zinc and iodine has the following cell notation. Zn(s) | Zn2+(aq) || I−(aq) | I2(s) | C(graphite) Which of the following equations correctly represents the balanced, spontaneous, cell reaction?

Given that E° for X + e- → Y is greater than E° for A + 2e- → B, it is correct to say that, under standard conditions

Calculate ΔG° for the oxidation of 3 moles of copper by nitric acid. Cu2+(aq) + 2e− ⇄ Cu(s) E° = 0.34 V NO3−(aq) + 4H+(aq) + 3e− ⇄ NO(g) + 2H2O(l) E° = 0.957 V

Which one of the following statements relating to the glass electrode is correct?

Which of the following elements can be isolated by electrolysis of the aqueous salt shown?

Which of the following statements about voltaic and electrolytic cells is correct?

Electrolytic cells utilize electrical energy to drive nonspontaneous redox reactions.

A salt bridge provides a path for electrons to move between the anode and cathode compartments of a voltaic cell.

What mass of silver will be formed when 15.0 A are passed through molten AgCl for 25.0 minutes?

What mass of copper will be deposited when 18.2 A are passed through a CuSO4 solution for 45.0 minutes?

Calculate E°cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. Co3+(aq) + e− ⇄ Co2+(aq) E° = 1.82 V MnO4−(aq) + 2H2O(l) + 3e- ⇄ MnO2(s) + 4OH−(aq) E° = 0.59 V Overall reaction: MnO4−(aq) + 2H2O(l) + 3Co2+(aq) → MnO2(s) + 3Co3+(aq) + 4OH−(aq)

A secondary cell (battery) can operate either as a galvanic or an electrolytic cell.

Keys to the Study of Chemistry: Definitions, Units, and Problem Solving

The Components of Matter

Stoichiometry of Formulas and Equations

Three Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Thermochemistry: Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids, Solids, and Phase Changes

The Properties of Mixtures: Solutions and Colloids

Periodic Patterns in the Main-Group Elements

Organic Compounds and the Atomic Properties of Carbon

Kinetics: Rates and Mechanisms of Chemical Reactions

Equilibrium: the Extent of Chemical Reactions

Acid-Base Equilibria

Ionic Equilibria in Aqueous Systems

Thermodynamics: Entropy, Free Energy, and Reaction Direction

The Elements in Nature and Industry

Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

A voltaic cell prepared using aluminum and nickel has the following cell notation. Al(s) | Al³⁺(aq) || Ni²⁺(aq) | Ni(s) Which of the following represents the correctly balanced spontaneous reaction equation for the cell?

Chromium metal is electroplated from acidic aqueous solutions containing the dichromate ion, Cr₂O₇²^-. What is the minimum time needed to plate out 10.0 g of chromium metal from such a solution, if the current is 50.0 A?

What is the E°_cell for the cell represented by the combination of the following half-reactions? 2Hg²⁺(aq) + 2e^- ⇄ Hg₂²⁺(aq) E° = 0.92 V Cr³⁺(aq) + 3e^- ⇄ Cr(s) E° = -0.74 V

A voltaic cell prepared using zinc and iodine has the following cell notation. Zn(s) | Zn²⁺(aq) || I⁻(aq) | I₂(s) | C(graphite) Which of the following equations correctly represents the balanced, spontaneous, cell reaction?

Given that E° for X + e^- → Y is greater than E° for A + 2e^- → B, it is correct to say that, under standard conditions

Calculate ΔG° for the oxidation of 3 moles of copper by nitric acid. Cu²⁺(aq) + 2e⁻ ⇄ Cu(s) E° = 0.34 V NO₃⁻(aq) + 4H⁺(aq) + 3e⁻ ⇄ NO(g) + 2H₂O(l) E° = 0.957 V

What mass of copper will be deposited when 18.2 A are passed through a CuSO₄ solution for 45.0 minutes?