Question 1

If the electrodes of a voltaic cell are connected with an external wire, electrons will flow in this wire from the cathode to the anode.

Accepted Answer

A) True 
 B)False

Question 2

Calculate E°cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. I2(s) + 2e− ⇄ 2I− (aq) E° = 0.53 V
Cr3+(aq) + 3e− ⇄ Cr(s) E° = −0.74 V
Overall reaction:
2Cr(s) + 3I2(s) → 2Cr3+(aq) + (aq) + 6I−(aq)

Accepted Answer

A) E° cell = −1.27 V, spontaneous 
B) E° cell = −1.27 V, nonspontaneous 
C) E° cell = 1.27 V, spontaneous 
D) E° cell = 1.27 V, nonspontaneous 
E) E° cell = 1.54 V, spontaneous 
A) E° cell = −1.27 V, spontaneous 
B) E° cell = −1.27 V, nonspontaneous 
C) E° cell = 1.27 V, spontaneous 
D) E° cell = 1.27 V, nonspontaneous 
E) E° cell = 1.54 V, spontaneous

Question 3

Which of the following conditions is most likely to apply to a fully-charged secondary cell?

Accepted Answer

A) E cell = E° cell 
B) E° cell = 0 
C) Q = 1 
D) Q < K 
E) Q = K 
A) E cell = E° cell 
B) E° cell = 0 
C) Q = 1 
D) Q < K 
E) Q = K

Question 4

Consider the following balanced redox reaction 3CuO(s) + 2NH3(aq) → N2(g) + 3H2O(l) + 3Cu(s)
Which of the following statements is true?

Accepted Answer

A) CuO( s)is the oxidizing agent and copper is reduced. 
B) CuO( s)is the oxidizing agent and copper is oxidized. 
C) CuO( s)is the reducing agent and copper is oxidized. 
D) CuO( s)is the reducing agent and copper is reduced. 
E) CuO( s)is the oxidizing agent and N 2( g)is the reducing agent. 
A) CuO( s)is the oxidizing agent and copper is reduced. 
B) CuO( s)is the oxidizing agent and copper is oxidized. 
C) CuO( s)is the reducing agent and copper is oxidized. 
D) CuO( s)is the reducing agent and copper is reduced. 
E) CuO( s)is the oxidizing agent and N 2( g)is the reducing agent.

Question 5

A voltaic cell consists of a Mn/Mn2+ electrode (E° = −1.18 V) and a Fe/Fe2+ electrode (E° = −0.44 V). Calculate [Fe2+] if [Mn2+] = 0.050 M and Ecell = 0.78 V at 25°C.

Accepted Answer

A) 0.040 M 
B) 0.24 M 
C) 1.1 M 
D) 1.8 M 
E) None of these choices are correct. 
A) 0.040 M 
B) 0.24 M 
C) 1.1 M 
D) 1.8 M 
E) None of these choices are correct.

Question 6

When metal A is placed in a solution of metal ions B2+, a reaction occurs between A and B2+, and metal ions A2+ appear in the solution. When metal B is placed in acid solution, gas bubbles form on its surface. When metal A is placed in a solution of metal ions C2+, no reaction occurs. Which of the following reactions would not occur spontaneously?

Accepted Answer

A) C( s)+ 2H +( aq)→ H 2( g)+ C 2+( aq) 
B) C( s)+ A 2+( aq)→ A( s)+ C 2+( aq) 
C) B( s)+ C 2+( aq)→ C( s)+ B 2+( aq) 
D) A( s)+ 2H +( aq)→ H 2( g)+ A 2+( aq) 
E) B( s)+ 2H +( aq)→ H 2( g)+ B 2+( aq) 
A) C( s)+ 2H +( aq)→ H 2( g)+ C 2+( aq) 
B) C( s)+ A 2+( aq)→ A( s)+ C 2+( aq) 
C) B( s)+ C 2+( aq)→ C( s)+ B 2+( aq) 
D) A( s)+ 2H +( aq)→ H 2( g)+ A 2+( aq) 
E) B( s)+ 2H +( aq)→ H 2( g)+ B 2+( aq)

Question 7

Calculate the potential of a voltaic cell (E°cell) if it is required to do 5.43 × 10−3 kJ of work when a charge of 2.50 C is transferred.

Accepted Answer

A) 2.17 × 10 3 V 
B) 2.17 × 10 −3 V 
C) 2.17 V 
D) 13.6 V 
E) 1.36 × 10 −2 V 
A) 2.17 × 10 3 V 
B) 2.17 × 10 −3 V 
C) 2.17 V 
D) 13.6 V 
E) 1.36 × 10 −2 V

Question 8

What is the value of the equilibrium constant for the cell reaction below at 25°C? E°cell = 0.61 V 2Cr(s) + 3Pb2+(aq) ⇄ 3Pb(s) + 2Cr3+(aq)

Accepted Answer

A) 4.1 × 10 20 
B) 8.2 × 10 30 
C) 3.3 × 10 51 
D) 7.4 × 10 61 
E) > 9.9 × 10 99 
A) 4.1 × 10 20 
B) 8.2 × 10 30 
C) 3.3 × 10 51 
D) 7.4 × 10 61 
E) > 9.9 × 10 99

Question 9

A voltaic cell consists of a Hg/Hg22+ electrode (E° = 0.85 V) and a Sn/Sn2+ electrode (E° = −0.14 V). Calculate [Sn2+] if [Hg22+] = 0.24 M and Ecell = 1.04 V at 25°C.

Accepted Answer

A) 0.0001 M 
B) 0.0007 M 
C) 0.005 M 
D) 0.03 M 
E) 0.05 M 
A) 0.0001 M 
B) 0.0007 M 
C) 0.005 M 
D) 0.03 M 
E) 0.05 M

Question 10

A voltaic cell consists of an Au/Au3+ electrode (E° = 1.50 V) and a Cu/Cu2+ electrode (E° = 0.34 V). Calculate [Au3+] if [Cu2+] = 1.20 M and Ecell = 1.13 V at 25°C.

Accepted Answer

A) 0.001 M 
B) 0.002 M 
C) 0.01 M 
D) 0.02 M 
E) 0.04 M 
A) 0.001 M 
B) 0.002 M 
C) 0.01 M 
D) 0.02 M 
E) 0.04 M

Question 11

Examine the following half-reactions and select the strongest oxidizing agent among the species listed. Cr2+(aq) + 2e− ⇄ Cr(s) E° = -0.913 V
Fe2+(aq) + 2e−⇄ Fe(s) E° = -0.447 V
Sr2+(aq) + 2e−⇄ Sr(s) E° = -2.89 V
Co2+(aq) + 2e−⇄ Co(s) E° = -0.28 V

Accepted Answer

A) Cr 2+( aq) 
B) Fe( s) 
C) Fe 2+( aq) 
D) Sr 2+( aq) 
E) Co 2+( aq) 
A) Cr 2+( aq) 
B) Fe( s) 
C) Fe 2+( aq) 
D) Sr 2+( aq) 
E) Co 2+( aq)

Question 12

If the equilibrium constant Kc is greater than 1 for a given reaction, predict the signs of ΔG° and E° at the same temperature.

Accepted Answer

A) Δ G° > 0; E° > 0 
B) ΔG°  0; E°  0 
E) Cannot predict - it depends on the temperature. 
A) Δ G° > 0; E° > 0 
B) ΔG°  0; E°  0 
E) Cannot predict - it depends on the temperature.

Question 13

In the electrolysis of aqueous potassium nitrate using inert electrodes, which one of the following species is oxidized?

Accepted Answer

A) Potassium ion 
B) Nitrate ion 
C) Water 
D) Oxygen 
E) Hydronium ion 
A) Potassium ion 
B) Nitrate ion 
C) Water 
D) Oxygen 
E) Hydronium ion

Question 14

Consider the following redox equation Mn(OH)2(s) + MnO4(aq) → MnO42−(aq) (basic solution)
When the equation is balanced with smallest whole number coefficients, what is the coefficient for OH−(aq) and on which side of the equation is OH−(aq) present?

Accepted Answer

A) 4, reactant side 
B) 4, product side 
C) 6, reactant side 
D) 6, product side 
E) None of these choices are correct. 
A) 4, reactant side 
B) 4, product side 
C) 6, reactant side 
D) 6, product side 
E) None of these choices are correct.

Question 15

Which of the following elements could be prepared by electrolysis of the aqueous solution shown?

Accepted Answer

A) Sodium from Na 3PO 4( aq) 
B) Sulfur from K 2SO 4( aq) 
C) Oxygen from H 2SO 4( aq) 
D) Potassium from KCl( aq) 
E) Nitrogen from AgNO 3( aq) 
A) Sodium from Na 3PO 4( aq) 
B) Sulfur from K 2SO 4( aq) 
C) Oxygen from H 2SO 4( aq) 
D) Potassium from KCl( aq) 
E) Nitrogen from AgNO 3( aq)

Question 16

A buried iron pipe can be protected against corrosion by connecting it to a rod of copper.

Accepted Answer

A) True 
 B)False

Question 17

Which one of the following pairs of substances could be used to construct a single redox electrode (i.e., they have an element in common, but in different oxidation states)?

Accepted Answer

A) HCl and Cl − 
B) H + and OH − 
C) H 2O and H + 
D) Fe 3+ and Fe 2O 3 
E) MnO 2 and Mn 2+ 
A) HCl and Cl − 
B) H + and OH − 
C) H 2O and H + 
D) Fe 3+ and Fe 2O 3 
E) MnO 2 and Mn 2+

Question 18

When the following redox equation is balanced with smallest whole number coefficients, the coefficient for zinc will be Zn(s) + ReO4(aq) → Re(s) + Zn2+(aq) (acidic solution)

Accepted Answer

A) 2. 
B) 7. 
C) 8. 
D) 16. 
E) None of these choices are correct. 
A) 2. 
B) 7. 
C) 8. 
D) 16. 
E) None of these choices are correct.

Question 19

Consider the reaction CuO(s) + H2(g) → Cu(s) + H2O(l)
In this reaction, which substances are the oxidant and reductant, respectively?

Accepted Answer

A) CuO and H 2 
B) H 2 and CuO 
C) CuO and Cu 
D) H 2O and H 2 
E) None of these choices are correct. 
A) CuO and H 2 
B) H 2 and CuO 
C) CuO and Cu 
D) H 2O and H 2 
E) None of these choices are correct.

Question 20

Examine the following half-reactions and select the strongest reducing agent among the species listed. HgO(s) + H2O(l) + 2e− ⇄ Hg(l) + 2OH−(aq) E° = 0.0977 V
Zn(OH)2(s) + 2e− ⇄ Zn(s) + 2OH−(aq) E° = −1.25 V
Ag2O(s) + H2O(l) + 2e− ⇄ Ag(s) + 2OH−(aq) E° = 0.342 V
B(OH)3(aq) + 7H+(aq) + 8e− ⇄ BH4−(aq) + 3H2O(l) E° = −0.481 V

Accepted Answer

A) Hg( l) 
B) Zn( s) 
C) Ag( s) 
D) BH 4 −( aq) 
E) Zn(OH)2( s) 
A) Hg( l) 
B) Zn( s) 
C) Ag( s) 
D) BH 4 −( aq) 
E) Zn(OH)2( s)

Exam 21: Electrochemistry: Chemical Change and Electrical Work

If the electrodes of a voltaic cell are connected with an external wire, electrons will flow in this wire from the cathode to the anode.

Calculate E°cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. I2(s) + 2e− ⇄ 2I− (aq) E° = 0.53 V Cr3+(aq) + 3e− ⇄ Cr(s) E° = −0.74 V Overall reaction: 2Cr(s) + 3I2(s) → 2Cr3+(aq) + (aq) + 6I−(aq)

Which of the following conditions is most likely to apply to a fully-charged secondary cell?

Consider the following balanced redox reaction 3CuO(s) + 2NH3(aq) → N2(g) + 3H2O(l) + 3Cu(s) Which of the following statements is true?

A voltaic cell consists of a Mn/Mn2+ electrode (E° = −1.18 V) and a Fe/Fe2+ electrode (E° = −0.44 V). Calculate [Fe2+] if [Mn2+] = 0.050 M and Ecell = 0.78 V at 25°C.

Calculate the potential of a voltaic cell (E°cell) if it is required to do 5.43 × 10−3 kJ of work when a charge of 2.50 C is transferred.

What is the value of the equilibrium constant for the cell reaction below at 25°C? E°cell = 0.61 V 2Cr(s) + 3Pb2+(aq) ⇄ 3Pb(s) + 2Cr3+(aq)

A voltaic cell consists of a Hg/Hg22+ electrode (E° = 0.85 V) and a Sn/Sn2+ electrode (E° = −0.14 V). Calculate [Sn2+] if [Hg22+] = 0.24 M and Ecell = 1.04 V at 25°C.

A voltaic cell consists of an Au/Au3+ electrode (E° = 1.50 V) and a Cu/Cu2+ electrode (E° = 0.34 V). Calculate [Au3+] if [Cu2+] = 1.20 M and Ecell = 1.13 V at 25°C.

Examine the following half-reactions and select the strongest oxidizing agent among the species listed. Cr2+(aq) + 2e− ⇄ Cr(s) E° = -0.913 V Fe2+(aq) + 2e−⇄ Fe(s) E° = -0.447 V Sr2+(aq) + 2e−⇄ Sr(s) E° = -2.89 V Co2+(aq) + 2e−⇄ Co(s) E° = -0.28 V

If the equilibrium constant Kc is greater than 1 for a given reaction, predict the signs of ΔG° and E° at the same temperature.

In the electrolysis of aqueous potassium nitrate using inert electrodes, which one of the following species is oxidized?

Consider the following redox equation Mn(OH)2(s) + MnO4(aq) → MnO42−(aq) (basic solution) When the equation is balanced with smallest whole number coefficients, what is the coefficient for OH−(aq) and on which side of the equation is OH−(aq) present?

Which of the following elements could be prepared by electrolysis of the aqueous solution shown?

A buried iron pipe can be protected against corrosion by connecting it to a rod of copper.

Which one of the following pairs of substances could be used to construct a single redox electrode (i.e., they have an element in common, but in different oxidation states)?

When the following redox equation is balanced with smallest whole number coefficients, the coefficient for zinc will be Zn(s) + ReO4(aq) → Re(s) + Zn2+(aq) (acidic solution)

Consider the reaction CuO(s) + H2(g) → Cu(s) + H2O(l) In this reaction, which substances are the oxidant and reductant, respectively?

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

Calculate E°_cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. I₂(s) + 2e⁻ ⇄ 2I⁻ (aq) E° = 0.53 V Cr³⁺(aq) + 3e⁻ ⇄ Cr(s) E° = −0.74 V Overall reaction: 2Cr(s) + 3I₂(s) → 2Cr³⁺(aq) + (aq) + 6I⁻(aq)

Consider the following balanced redox reaction 3CuO(s) + 2NH₃(aq) → N₂(g) + 3H₂O(l) + 3Cu(s) Which of the following statements is true?

A voltaic cell consists of a Mn/Mn²⁺ electrode (E° = −1.18 V) and a Fe/Fe²⁺ electrode (E° = −0.44 V). Calculate [Fe²⁺] if [Mn²⁺] = 0.050 M and E_cell = 0.78 V at 25°C.

Calculate the potential of a voltaic cell (E°_cell) if it is required to do 5.43 × 10⁻³ kJ of work when a charge of 2.50 C is transferred.

What is the value of the equilibrium constant for the cell reaction below at 25°C? E°_cell = 0.61 V 2Cr(s) + 3Pb²⁺(aq) ⇄ 3Pb(s) + 2Cr³⁺(aq)

A voltaic cell consists of a Hg/Hg₂²⁺ electrode (E° = 0.85 V) and a Sn/Sn²⁺ electrode (E° = −0.14 V). Calculate [Sn²⁺] if [Hg₂²⁺] = 0.24 M and E_cell = 1.04 V at 25°C.

A voltaic cell consists of an Au/Au³⁺ electrode (E° = 1.50 V) and a Cu/Cu²⁺ electrode (E° = 0.34 V). Calculate [Au³⁺] if [Cu²⁺] = 1.20 M and E_cell = 1.13 V at 25°C.

Examine the following half-reactions and select the strongest oxidizing agent among the species listed. Cr²⁺(aq) + 2e⁻⇄ Cr(s) E° = -0.913 V Fe²⁺(aq) + 2e⁻⇄ Fe(s) E° = -0.447 V Sr²⁺(aq) + 2e⁻⇄ Sr(s) E° = -2.89 V Co²⁺(aq) + 2e⁻⇄ Co(s) E° = -0.28 V

If the equilibrium constant K_c is greater than 1 for a given reaction, predict the signs of ΔG° and E° at the same temperature.

Consider the following redox equation Mn(OH)₂(s) + MnO₄(aq) → MnO₄²⁻(aq) (basic solution) When the equation is balanced with smallest whole number coefficients, what is the coefficient for OH⁻(aq) and on which side of the equation is OH⁻(aq) present?

When the following redox equation is balanced with smallest whole number coefficients, the coefficient for zinc will be Zn(s) + ReO₄(aq) → Re(s) + Zn²⁺(aq) (acidic solution)

Consider the reaction CuO(s) + H₂(g) → Cu(s) + H₂O(l) In this reaction, which substances are the oxidant and reductant, respectively?