Deck 20: Principles of Reactivity: Electron Transfer Reactions

Question 1

How many electrons are transferred in the following reaction?

A) 0
B) 1
C) 2
D) 3
E) 4

Answer 1

2

Question 2

Which of the following statements is true concerning the voltaic cell shown below?

A) The Zn anode mass decreases as the cell discharges.
B) The Zn cathode mass increases as the cell discharges.
C) The Zn cathode mass decreases as the cell discharges.
D) The Zn anode mass increases as the cell discharges.
E) The mass of the Zn electrode neither increases nor decreases as the cell discharges.

Answer 2

The Zn anode mass decreases as the cell discharges.

Question 3

When the following oxidation-reduction reaction in acidic solution is balanced,what is the lowest whole-number coefficient for H⁺,and on which side of the balanced equation should it appear?
MnO₄^-(aq)+ I^-(aq) $\to$ Mn²⁺(aq)+ I₂(s)

A) 1,reactant side
B) 2,product side
C) 8,reactant side
D) 16,reactant side
E) 4,product side

Answer 3

16,reactant side

Question 4

Write a balanced chemical equation for the oxidation of Cd(s)by concentrated nitric acid,producing NO₂(g)and Cd²⁺(aq).

A) HNO₃(aq)+ Cd(s) $\to$ Cd²⁺(aq)+ NO₂(g)+ OH^-(aq)
B) 2 HNO₃(aq)+ Cd(s) $\to$ Cd²⁺(aq)+ 2 NO₂(g)+ 2 OH^-(aq)
C) HNO₃(aq)+ Cd(s)+ H⁺(aq) $\to$ Cd²⁺(aq)+ NO₂(g)+ H₂O( )
D) 4 HNO₃(aq)+ Cd(s) $\to$ Cd²⁺(aq)+ 2 NO₂(g)+ 2H₂O( )+ 2 NO₃^-(aq)
E) HNO₃(aq)+ Cd(s) $\to$ Cd²⁺(aq)+ NO₂(g)

Question 5

Write a balanced half-reaction for the reduction of CrO₄^2-(aq)to Cr(OH)₃(s)in a basic solution.

A) CrO₄^2-(aq)+ 3 OH^-(aq)+ 3 e^- $\to$ Cr(OH)₃(s)+ 2 O₂(g)
B) CrO₄^2-(aq)+ 3 H⁺(aq)+ 3 e^- $\to$ Cr(OH)₃(s)
C) CrO₄^2-(aq)+ 3 H⁺(aq) $\to$ Cr(OH)₃(s)+ 2 e^-
D) CrO₄^2-(aq)+ 4 H₂O( )+ 3 e^- $\to$ Cr(OH)₃(s)+ 5 OH^-(aq)
E) CrO₄^2-(aq)+ 3 OH^-(aq) $\to$ Cr(OH)₃(s)+ 2 O₂(g)

Question 6

All of the following statements concerning voltaic cells are true EXCEPT

A) a salt bridge allows cations and anions to move between the half-cells.
B) electrons flow from the cathode to the anode in the external circuit.
C) oxidation occurs at the anode.
D) a voltaic cell can be used as a source of energy.
E) a voltaic cell consists of two-half cells.

Question 7

Assuming the following reaction proceeds in the forward direction,
Fe³⁺(aq)+ Co(s) $\to$ Fe²⁺(aq)+ Co²⁺(aq)

A) Fe³⁺(aq)is oxidized and Co(s)is reduced.
B) Fe³⁺(aq)is oxidized and Co²⁺(aq)is reduced.
C) Co(s)is oxidized and Fe³⁺(aq)is reduced.
D) Co(s)is oxidized and Co²⁺(aq)is reduced.
E) Fe²⁺(aq)is oxidized and Co(s)is reduced.

Question 8

Assuming the following reaction proceeds in the forward direction,
3 Sn⁴⁺(aq)+ 2 Cr(s) $\to$ 3 Sn²⁺(aq)+ 2 Cr³⁺(aq)

A) Sn⁴⁺(aq)is the reducing agent and Cr(s)is the oxidizing agent.
B) Cr(s)is the reducing agent and Sn²⁺(aq)is the oxidizing agent.
C) Sn⁴⁺(aq)is the reducing agent and Sn²⁺(aq)is the oxidizing agent.
D) Cr(s)is the reducing agent and Cr³⁺(aq)is the oxidizing agent.
E) Cr(s)is the reducing agent and Sn⁴⁺(aq)is the oxidizing agent.

Question 9

The following reaction occurs spontaneously.
2 H⁺(aq)+ Ca(s) $\to$ Ca²⁺(aq)+ H₂(g)
Write the balanced oxidation half-reaction.

A) 2 H⁺(aq)+ 2 e^- $\to$ H₂(g)
B) 2 H⁺(aq) $\to$ H₂(g)+ 2 e^-
C) H₂(g) $\to$ 2 H⁺(aq)+ 2 e^-
D) Ca(s)+ 2 e^- $\to$ Ca²⁺(aq)
E) Ca(s) $\to$ Ca²⁺(aq)+ 2 e^-

Question 10

Balance the following oxidation-reduction occurring in acidic solution.
MnO₄^-(aq)+ Cr²⁺(aq) $\to$ Mn²⁺(aq)+ Cr³⁺(aq)

A) MnO₄^-(aq)+ 8H⁺(aq)+ 5Cr²⁺(aq) $\to$ Mn²⁺(aq)+ 4H₂O( $\ell$ )+ 5Cr³⁺(aq)
B) MnO₄^-(aq)+ 8H⁺(aq)+ Cr²⁺(aq) $\to$ Mn²⁺(aq)+ 4H₂O( $\ell$ )+ Cr³⁺(aq)
C) MnO₄^-(aq)+ 4H₂(g)+ 5Cr²⁺(aq) $\to$ Mn²⁺(aq)+ 4H₂O( $\ell$ )+ 5Cr³⁺(aq)
D) MnO₄^-(aq)+ 8H⁺(aq)+ 2Cr²⁺(aq) $\to$ Mn²⁺(aq)+ 4H₂O( $\ell$ ) + 2Cr³⁺(aq)
E) MnO₄^-(aq)+ Cr²⁺(aq) $\to$ Mn²⁺(aq)+ 2O₂(g)+ Cr³⁺(aq)

Question 11

Write a balanced chemical equation for the following reaction in a basic solution.
ClO^-(aq)+ Cr(OH)₃(s) $\to$ Cl^-(aq)+ CrO₄^2-(aq)

A) 3 ClO^-(aq)+ 2 Cr(OH)₃(s)+ 4 OH^-(aq) $\to$ 3 Cl^-(aq)+ 2 CrO₄^2-(aq)+ 5 H₂O( )
B) ClO^-(aq)+ Cr(OH)₃(s)+ 3 OH^-(aq) $\to$ Cl^-(aq)+ CrO₄^2-(aq)+ 3 H₂O( )
C) 2 ClO^-(aq)+ 3 Cr(OH)₃(s)+ 3 OH^-(aq) $\to$ 2 Cl^-(aq)+ 3 CrO₄^2-(aq)+ 6 H₂O( )
D) 4 ClO^-(aq)+ Cr(OH)₃(s)+ 4 OH^-(aq) $\to$ Cl^-(aq)+ CrO₄^2-(aq)+ 6 H₂O( )
E) ClO^-(aq)+ Cr(OH)₃(s) $\to$ Cl^-(aq)+ CrO₄^2-(aq)+ 3 H⁺(aq)

Question 12

Write a balanced half-reaction for the reduction of hydrogen peroxide to water in an acidic solution.

A) 2 H₂O₂( ) $\to$ 2 H₂O( )+ O₂(g)
B) 2 H₂O₂( )+ 2e^- $\to$ 2 H₂O( )+ O₂(g)
C) H₂O₂( )+ 2 H⁺(aq)+ 2 e^- $\to$ 2 H₂O( )
D) H₂O₂( )+ 4 H⁺(aq)+ 2 e^- $\to$ 2 H₂O( )+ H₂(g)
E) H₂O₂( )+ 2 H⁺(aq)+ 4 e^- $\to$ 2 H₂(g)+ O₂(g)

Question 13

Which of the following reactions would require the use of an inert electrode when used in a voltaic cell?

A) Cu(s)+ 2Ag⁺(aq) $\to$ 2Ag(s)+ Cu²⁺(aq)
B) 3Cu(s)+ 2Au³⁺(aq) $\to$ 3Cu²⁺ + 2Au(s)
C) Cu(s)+ 2Ag⁺(aq) $\to$ Cu²⁺(aq)+ 2Ag(s)
D) Co(s)+ 2MnO₂(s)+ 2NH₄⁺(aq) $\to$ Co²⁺(aq)+ Mn₂O₃(s)+ 2NH₃(aq)+ H₂O( $\ell$ )
E) 3Zn²⁺(aq)+ 2Al(s) $\to$ 3Zn(s)+ 2Al³⁺(aq)

Question 14

Balance the following half-reaction occurring in acidic solution.
NO₃^-(aq) $\to$ HNO₂(aq)

A) NO₃^-(aq)+ 3H⁺(aq)+ 2e^- $\to$ HNO₂(aq)+ H₂O( $\ell$ )
B) NO₃^-(aq)+ H₂O( $\ell$ )+ 2e^- $\to$ HNO₂(aq)+ 3H⁺(aq)
C) NO₃^-(aq)+ 3H⁺(aq) $\to$ HNO₂(aq)+ H₂O( $\ell$ )+ 2e^-
D) NO₃^-(aq)+ 2e^- $\to$ HNO₂(aq)+ 3H⁺(aq)+ H₂O( $\ell$ )
E) NO₃^-(aq)+ 3H⁺(aq) $\to$ HNO₂(aq)+ H₂O(λ)

Question 15

When the following oxidation-reduction reaction in acidic solution is balanced,what is the lowest whole-number coefficient for K⁺(aq)?
K(s)+ Ca²⁺(aq) $\to$ K⁺(aq)+ Ca(s)

A) 5
B) 4
C) 1
D) 3
E) 2

Question 16

The following reaction occurs spontaneously.
2 Fe(s)+ 3 Cl₂(aq) $\to$ 2 Fe³⁺(aq)+ 6 Cl^-(aq)
Write the balanced oxidation half-reaction.

A) Fe(s) $\to$ Fe³⁺(aq)+ 3 e^-
B) Fe(s)+ 3 e^- $\to$ Fe³⁺(aq)
C) Fe(s)+ 3/2 Cl₂(aq) $\to$ FeCl₃(aq)
D) Cl₂(aq) $\to$ 2 Cl^-(aq)+ 2 e^-
E) Cl₂(aq)+ 2 e^- $\to$ 2 Cl^-(aq)

Question 17

Which of the following statements concerning a voltaic cell is/are correct?
1)Reduction occurs at the cathode.
2)A spontaneous reaction generates an electric current in a voltaic cell.
3)Without a salt bridge charge buildup will cause the cell reaction to stop.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1,2,and 3

Question 18

Which of the following statements is true concerning half-cell II as the voltaic cell shown below discharges?

A) [Cu²⁺] decreases with time,and [K⁺] increases with time.
B) [Cu²⁺] increases with time,and [K⁺] increases with time.
C) [Cu²⁺] decreases with time,and [K⁺] decreases with time.
D) [Cu²⁺] decreases with time,and [SO₄^-] decreases with time.
E) [Cu²⁺] increases with time,and [SO₄^-] increases with time.

Question 19

Write a balanced chemical equation for the following reaction in an acidic solution.Cr₂O₇^2-(aq)+ Ni(s) $\to$ Cr³⁺(aq)+ Ni²⁺(aq)

A) Cr₂O₇^2-(aq)+ 3 Ni(s)+ 14 H⁺(aq) $\to$ 2 Cr³⁺(aq)+ 3 Ni²⁺(aq)+ 7 H₂O( )
B) Cr₂O₇^2-(aq)+ Ni(s)+ 14 H⁺(aq) $\to$ 2 Cr³⁺(aq)+ Ni²⁺(aq)+ 7 H₂O( )
C) Cr₂O₇^2-(aq)+ 3 Ni(s) $\to$ 2 Cr³⁺(aq)+ 3 Ni²⁺(aq)+ O^2-(aq)
D) Cr₂O₇^2-(aq)+ Ni(s)+ 14 H⁺(aq) $\to$ 2 Cr³⁺(aq)+ Ni²⁺(aq)+ 7 H₂O( )
E) Cr₂O₇^2-(aq)+ 3 Ni(s)+ 7 H⁺(aq) $\to$ 2 Cr³⁺(aq)+ 3 Ni²⁺(aq)+ 7 OH^-(aq)

Question 20

Balance the following half-reaction occurring in basic solution.
MnO₂(s) $\to$ Mn(OH)₂(s)

A) MnO₂(s)+ 2H₂O( $\ell$ )+ 2e^- $\to$ Mn(OH)₂(s)+ 2OH^-(aq)
B) MnO₂(s)+ 2H₂O( $\ell$ )+ 4e^- $\to$ Mn(OH)₂(s)+ (OH)₂^-(aq)
C) MnO₂(s)+ H₂²⁺(aq)+ 2e^- $\to$ Mn(OH)₂(s)
D) MnO₂(s)+ H₂(g) $\to$ Mn(OH)₂(s)+ 2e^-
E) MnO₂(s)+ 2H₂O( $\ell$ ) $\to$ Mn(OH)₂(s)+ 2OH^-(aq)

Question 21

What is the correct cell notation for a voltaic cell based on the reaction below?
Cu²⁺(aq)+ Fe(s) $\to$ Cu(s)+ Fe²⁺(aq)

A) Cu(s)| Cu²⁺(aq)|| Fe²⁺(aq)| Fe(s)
B) Fe(s)|| Fe²⁺(aq),Cu²⁺(aq)| Cu(s)
C) Cu(s)|| Cu²⁺(aq),Fe²⁺(aq)|| Fe(s)
D) Cu(s)| Fe²⁺(aq)|| Cu²⁺(aq)| Fe(s)
E) Fe(s)| Fe²⁺(aq)|| Cu²⁺(aq)| Cu(s)

Question 22

Use the standard reduction potentials below to determine which element or ion is the best oxidizing agent.
O₂(g)+ 4 H⁺(aq)+ 4 e^- $\to$ 2 H₂O( ) $~~~~~~~~$$~~~~~~~~$ E ^$\circ$ = +1.229 V
Hg₂²⁺(aq)+ 2 e^- $\to$ 2 Hg( ) $~~~~~~~~$$~~~~~~~~$$~~ ~ ~~~$$~ ~~~$ E ^$\circ$ = +0.789 V
I₂(s)+ 2 e^- $\to$ 2 I^-(aq) $~~~~~~~~$$~~ ~~~~$$~~~~~~~~$$~~~~~~~~$$~~ ~~~~~$ E ^$\circ$ = +0.535 V

A) I₂(s)
B) O₂(g)
C) I^-(aq)
D) Hg₂²⁺(aq)
E) H₂O( )

Question 23

Which of the following statements is/are CORRECT?
1)A nickel-cadmium battery is an example of a secondary or rechargeable battery,often used in rechargeable cordless appliances.
2)Hydrogen-oxygen fuel cells use the heat of combustion of hydrogen to recharge lead storage batteries.
3)LeClanché cells are the most efficient rechargeable batteries,but they are rarely used due their high cost of production.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 3
E) 1,2,and 3

Question 24

Given:
Mn²⁺(aq)+ 2e^- $\to$ Mn(s); E° = -1.18 V
Cu²⁺(aq)+ 2e^- $\to$ Cu(s); E° = 0.34 V
Cr₂O₇^2-(aq)+ 14H⁺(aq)+ 6e^- $\to$ 2Cr³⁺(aq)+ 7H₂O(l); E° = 1.33 V
Which of the following species is the strongest reducing agent?

A) Mn
B) Cu
C) Cr³⁺
D) Mn²⁺
E) Cr₂O₇^2-

Question 25

The electrochemical reaction which powers a lead-acid storage battery is as follows:
Pb(s)+ PbO₂(s)+ 4H⁺(aq)+ 2SO₄^2-(aq) $\to$ 2PbSO₄(s)+ 2H₂O(l)
A single cell of this battery consists of a Pb electrode and a PbO₂ electrode,each submerged in sulfuric acid.What reaction occurs at the cathode during discharge?

A) Pb(s)is reduced to PbSO₄(s).
B) PbO₂(s)is reduced to PbSO₄(s).
C) PbO₂(s)is oxidized to PbSO₄(s).
D) Pb(s)is oxidized to PbSO₄(s).
E) H⁺ is oxidized to H₂O(l).

Question 26

Write a balanced chemical equation for the overall reaction represented by the cell notation below.Mn(s)| Mn²⁺(aq)|| Zn²⁺(aq)| Zn(s)

A) 2Mn(s)+ Zn²⁺(aq) $\to$ Zn(s)+ 2Mn²⁺(aq)
B) Mn(s)+ Mn²⁺(aq) $\to$ Zn(s)+ Zn²⁺(aq)
C) Mn(s)+ Zn²⁺(aq) $\to$ Zn(s)+ Mn²⁺(aq)
D) 2Zn(s)+ Mn²⁺(aq) $\to$ Mn(s)+ 2Zn²⁺(aq)
E) Zn(s)+ Mn²⁺(aq) $\to$ Mn(s)+ Zn²⁺(aq)

Question 27

In the following electrochemical cell,what is the reduction half reaction?
Cu(s)| Cu²⁺(aq)|| Fe³⁺(aq),Fe²⁺(aq)| Pt(s)

A) Fe^3-(aq)+ e^- $\to$ Fe²(aq)
B) Fe^2-(aq)+ e^- $\to$ Fe³⁺(aq)
C) Fe²⁺(aq)+ Pt(s) $\to$ Fe³⁺0(aq)+ e^-
D) Cu²⁺(aq) $\to$ Cu(s)+ 2e^-
E) Cu(s) $\to$ Cu²⁺(aq)+ 2e^-

Question 28

Consider the following half-reactions:
Cl₂(g)+ 2 e^- $\to$ 2 Cl^-(aq) $~~~~~~~~$$~~~~~~~~$ E ^$\circ$ = +1.36 V
Ag⁺(aq)+ e^- $\to$ Ag(s) $~~~ ~~~~$$~~~~ ~~~$$~~ ~~~~$ E ^$\circ$ = +0.80 V
Cu²⁺(aq)+ 2 e^- $\to$ Cu(s) $~~~~~~~~$$~~~~~~~~$ E ^$\circ$ = +0.34 V
Sn²⁺(aq)+ 2 e^- $\to$ Sn(s) $~~~~~ ~$$~~~ ~$$~~~~~~~~$ E ^$\circ$ = -0.14 V
Al³⁺(aq)+ 3 e^- $\to$ Al(s) $~~~~~~~~$$~~~ ~~~~$$~~~$ E ^$\circ$ = -1.66 V
Which of the above elements or ions will reduce Cu²⁺(aq)?

A) Ag(s)and Sn²⁺(aq)
B) Cl^-(aq)and Ag(s)
C) Cl₂(g)and Ag⁺(aq)
D) Sn(s)and Al(s)
E) Sn²⁺(aq)and Al³⁺(aq)

Question 29

Which of the following are standard conditions for an electrochemical cell?
1)Solutes in aqueous solution has a concentration of 1 M.
2)Gaseous reactants or products have a pressure of 1 bar.
3)Solids are present in quantities of 1 mole.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1,2,and 3

Question 30

Which of the following species are likely to behave as oxidizing agents: Li(s),H₂(g),MnO₄^-(aq),and Cl^-(aq)?

A) Li(s)only
B) MnO₄^-(aq)only
C) H₂(g)and Cl^-(aq)
D) Li(s)and MnO₄^-(aq)
E) Cl^-(aq)only

Question 31

What is the balanced spontaneous reaction and standard cell potential of an electrochemical cell constructed from half cells with the following half reactions?
Fe²⁺(aq)+ 2e^- $\to$ Fe(s) $~~~~~~~~$$~~~~~~~~$ E° = -0.440 V
Pb²⁺(aq)+ 2e^- $\to$ Pb(s) $~~~~~~~~$$~~~~~~~~$ E° = -0.130 V

A) Pb²⁺(aq)+ Fe(s) $\to$ Pb(s)+ Fe²⁺(aq) =0.310 V
B) Pb(s)+ Fe²⁺(aq) $\to$ Pb²⁺(aq)+ Fe(s) =-0.310 V
C) Pb²⁺(aq)+ Fe²⁺(aq) $\to$ Pb(s)+ Fe(s) =-0.570 V
D) Pb²⁺(aq)+ Fe(s) $\to$ Pb(s)+ Fe²⁺(aq) =0.155 V
E) Pb(s)+ Fe²⁺(aq) $\to$ Pb²⁺(aq)+ Fe(s) =-0.155 V

Question 32

The fuel cells used aboard NASA's Space Shuttles are electrochemical cells that generate electricity from which overall chemical reaction?

A) Fe₂O₃(s)+ Al(s) $\to$ Fe(s)+ Al₂O₃(s)
B) Pb(s)+ PbO₂(s)+ 2 H₂SO₄(aq) $\to$ 2 PbSO₄(s)+ 2 H₂O( )
C) 2 NiO(OH)(s)+ Cd(s)+ H₂O( ) $\to$ 2 Ni(OH)₂(s)+ Cd(OH)₂(s)
D) 2 H₂(g)+ O₂(g) $\to$ 2 H₂O( )
E) N₂H₄( )+ O₂(g) $\to$ N₂(g)+ 2 H₂O( )

Question 33

Consider the following half-reactions:
Ag⁺(aq)+ e^- $\to$ Ag(s) $~~~~~~~~$$~~~~~~~~$ E ^$\circ$ = +0.80 V
Cu²⁺(aq)+ 2 e^- $\to$ Cu(s) $~~~~~~~~$$~ ~~ ~$ E ^$\circ$ = +0.34 V
Pb²⁺(aq)+ 2 e^- $\to$ Pb(s) $~~~~~~~~$$~~ ~ ~~$ E ^$\circ$ = -0.13 V
Fe²⁺(aq)+ 2 e^- $\to$ Fe(s) $~~~~~~~~$$~~ ~ ~~$ E ^$\circ$ = -0.44 V
Al³⁺(aq)+ 3 e^- $\to$ Al(s) $~~~~~~~~$$~~~ ~ ~$ E ^$\circ$ = -1.66 V
Which of the above metals or metal ions will oxidize Pb(s)?

A) Ag⁺(aq)and Cu²⁺(aq)
B) Ag(s)and Cu(s)
C) Fe²⁺(aq)and Al³⁺(aq)
D) Fe(s)and Al(s)
E) Cu²⁺(aq)and Fe²⁺(aq)

Question 34

Write a balanced chemical equation for the overall reaction represented by the cell notation below.
Al(s)| Al³⁺(aq)|| Br^-(aq)| Br₂(g)| Pt(s)

A) 2Al(s)+ 3Br₂(g) $\to$ 2Al³⁺(aq)+ 6Br^-(aq)
B) Al(s)+ Al³⁺(aq) $\to$ Br^-(aq)+ Br₂(g)
C) 2Al³⁺(aq)+ 6Br^-(aq) $\to$ 2Al(s)+ 3Br₂(g)
D) Al(s)+ 3Br₂(g) $\to$ Al³⁺(s)+ 2Br^-(aq)
E) Al(s)+ 2Br^-(aq) $\to$ Br₂(g)+ Al³⁺(aq)

Question 35

What is the correct cell notation for a cell in which the hydrogen electrode is the anode and the cathode half-reaction is
Pb⁴⁺(aq)+ 2e^- Pb²⁺(aq).

A) Pt(s)| H₂(g)| H⁺(aq)|| Pb⁴⁺(aq),Pb²⁺(aq)| Pt(s)
B) Pt(s)| H₂(g)| H⁺(aq)|| Pb⁴⁺(aq),Pb²⁺(aq)
C) Pb²⁺(aq),Pb⁴⁺(aq)|| H⁺(aq)| H₂(g)| Pt(s)
D) Pt(s)| Pb²⁺(aq),Pb⁴⁺(aq)|| H⁺(aq)| H₂(g)| Pt(s)
E) H₂(g)| H⁺(aq)|| Pb²⁺(aq),Pb⁴⁺(aq)

Question 36

What is a correct cell notation for a voltaic cell based on the reaction below?
Cu²⁺(aq)+ Pb(s)+ SO₄^2-(aq) $\to$ Cu(s)+ PbSO₄(s)

A) Pb(s)| PbSO₄(s)|| Cu²⁺(aq)|| Cu(s)
B) Cu(s)| Cu²⁺(aq)|| SO₄^2-(aq)| PbSO₄(s)| Pb(s)
C) Cu(s)| Cu²⁺(aq),SO₄^2-(aq)| PbSO₄(s)| Pb(s)
D) Cu(s)| Cu²⁺(aq),SO₄^2-(aq)|| PbSO₄(s)|| Pb(s)
E) Pb(s)| PbSO₄(s)| SO₄^2-(aq)|| Cu²⁺(aq)|| Cu(s)

Question 37

An SHE electrode has been assigned a standard reduction potential,E ^$\circ$ ,of 0.00 Volts.Which reaction occurs at this electrode?

A) 2 H₂O( )+ 2 e^- $\to$ H₂(g)+ 2 OH^-(aq)
B) O₂(g)+ 4 e^- $\to$ 2 O^2-(aq)
C) Hg₂Cl₂(s)+ 2 e^- $\to$ 2 Hg( )+ 2 Cl^-(aq)
D) Li⁺(aq)+ e^- $\to$ Li(s)
E) 2 H⁺(aq)+ 2 e^- $\to$ H₂(g)

Question 38

According to the following cell notation,which species is undergoing reduction?
Cu | Cu²⁺(aq)|| Mn²⁺(aq)| MnO₂(s)| Pt(s)

A) Mn²⁺(aq)
B) Cu²⁺(aq)
C) Cu(s)
D) MnO₂(s)
E) Pt(s)

Question 39

Given:
2H⁺(aq)+ 2e^- $\to$ H₂(g); 0.00 V
Rb⁺(aq)+ e^- $\to$ Rb(s); -2.98 V
F₂(g)+ 2e^- $\to$ 2F^-(aq); 2.87 V
Al³⁺(aq)+ 3e^- $\to$ Al(s); -1.66 V
Pb²⁺(aq)+ 2e^- $\to$ Pb(s); -0.13 V
Under standard-state conditions,which is the strongest reducing agent?

A) Al³⁺
B) H⁺
C) Pb²⁺
D) F^-
E) Rb

Question 40

The unit for electromotive force,emf,is the Volt.A Volt is equal to

A) one joule per second.
B) one coulomb per joule.
C) one joule per coulomb.
D) one coulomb per second.
E) one second per joule.

Question 41

Calculate for the electrochemical cell below,
Ag(s)| AgCl(s)| Cl^-(aq,1.0 M)|| Cu²⁺(aq,1.0 M)| Cu(s)
Given the following standard reduction potentials.

Cu²⁺(aq)+ 2 e^- $\to$ Cu(s) $~~~~~~~~$$~~~~~~~~$ E ^$\circ$ = +0.337 V
AgCl(s)+ e^- $\to$ Ag(s)+ Cl^-(aq) $~~~~~~~~$ E ^$\circ$ = +0.222 V

A) -0.115 V
B) -0.107 V
C) +0.115 V
D) +0.452 V
E) +0.559 V

Question 42

Calculate E_cell for the following electrochemical cell at 25°C given that the standard cell potential,
E°_cell,is 0.460 V.
Cu(s)| Cu²⁺(aq,0.012 M)|| Ag⁺(aq,0.17 M)| Ag(s)

A) 0.471 V
B) 0.282 V
C) 0.460 V
D) 0.494 V
E) 0.486 V

Question 43

What is the copper(II)-ion concentration at 25°C in the cell Zn(s)| Zn²⁺(aq,1.0 M)|| Cu²⁺(aq)| Cu(s)if the measured cell potential is 1.01 V? The standard cell potential is 1.10 V.

A) 0.030 M
B) 0.99 M
C) 0.00091 M
D) 1.0 M
E) 0.99M

Question 44

For the electrochemical cell Zn(s)| Zn²⁺ || Ag⁺ | Ag(s),the standard cell potential is 1.56 V.A cell using these reagents was made,and the observed potential was 1.44 V at 25^oC.What is a possible explanation for the observed voltage?

A) The volume of the Zn²⁺ solution was larger than the volume of the Ag⁺ solution.
B) The volume of the Ag⁺ solution was larger than the volume of the Zn²⁺ solution.
C) The Zn²⁺ concentration was larger than the Ag⁺ concentration.
D) The Ag electrode was twice as large as the Zn electrode.
E) The Ag⁺ concentration was larger than the Zn²⁺ concentration.

Question 45

The following electrochemical cell has a potential of +0.326 V at 25 ^$\circ$ C.Pt | H₂(g,1.00 atm)| H⁺(aq,1.00 M)|| Cl^-(aq)| AgCl(s)| Ag
The standard reduction potential,E ^$\circ$ ,of AgCl(s)= +0.222 V.What is the Cl^-(aq)concentration?

A) 1.9 $\times$ 10^-19 M
B) 5.5 $\times$ 10^-10 M
C) 0.018 M
D) 1.03 M
E) 1.8 $\times$ 10⁹ M

Question 46

What is the pH of the solution at the cathode if = -0.362 V for the following electrochemical cell at 25 ^$\circ$ C?
Pt | H₂(g,1.0 atm)| H⁺(aq,1.00 M)|| H⁺(aq)| H₂(g,1.0 atm)| Pt

A) 1.77
B) 3.06
C) 6.11
D) 7.89
E) 12.23

Question 47

A Faraday,F,is defined as

A) the charge on a single electron.
B) the charge,in coulombs,carried by one mole of electrons.
C) the voltage required to reduce one mole of reactant.
D) the moles of electrons required to reduce one mole of reactant.
E) the charge passed by one ampere of current in one second.

Question 48

Calculate for the electrochemical cell below,
Pb(s)|PbCl₂(s)| Cl^-(aq,1.0 M)|| Fe³⁺(aq,1.0 M),Fe²⁺(aq,1.0 M)| Pt(s)
Given the following reduction half-reactions.

Pb²⁺(aq)+ 2 e^- $\to$ Pb(s) $~~~ ~~~~$$~~~ ~~~~$$~~~~~~~~$ E ^$\circ$ = -0.126 V
PbCl₂(s)+ 2 e^- $\to$ Pb(s)+ 2 Cl^-(aq) $~~~~~~~~$ E ^$\circ$ = -0.267 V
Fe³⁺(aq)+ e^- $\to$ Fe²⁺(aq) $~~~~ ~$$~~~~~~~~$$~~~~~~~~$ E ^$\circ$ = +0.771 V
Fe²⁺(aq)+ e^- $\to$ Fe(s) $~~~~~~~~$$~~ ~~~~~$$~ ~ ~$$~~~~~~~~$ E ^$\circ$ = -0.44 V

A) -0.504 V
B) -0.062 V
C) +0.504 V
D) +1.038 V
E) +1.604 V

Question 49

Given the following two half-reactions,write the overall reaction in the direction in which it is spontaneous and calculate the standard cell potential.
Pb²⁺(aq)+ 2 e^- $\to$ Pb(s) $~~~~~~~~$$~~~~~~~~$ E ^$\circ$ = -0.126 V
Fe³⁺(aq)+ e^- $\to$ Fe²⁺(s) $~~~~~~~~$$~~~~~~~~$ E ^$\circ$ = +0.771 V

A) Pb²⁺(aq)+ 2 Fe²⁺(s) $\to$ Pb(s)+ 2 Fe³⁺(aq) = +0.897 V
B) Pb²⁺(aq)+ Fe²⁺(s) $\to$ Pb(s)+ Fe³⁺(aq) = +0.645 V
C) Pb(s)+ 2 Fe³⁺(aq) $\to$ Pb²⁺(aq)+ 2 Fe²⁺(s) = +1.416 V
D) Pb(s)+ 2 Fe³⁺(aq) $\to$ Pb²⁺(aq)+ 2 Fe²⁺(s) = +0.897 V
E) Pb(s)+ Fe³⁺(aq) $\to$ Pb²⁺(aq)+ Fe²⁺(s) = +0.645 V

Question 50

The following has a potential of 0.92 V: If the concentrations of the ions were 1.0 M and the pressure of H₂ were 1.0 atm,then E ^$\circ$ for the half-reaction
Would be

A) 0.46 V
B) -0.46 V
C) 0.92 V
D) -0.92 V
E) none of these

Question 51

Calculate the cell potential,at 25 ^$\circ$ C,based upon the overall reaction
Zn²⁺(aq)+ 2 Fe²⁺(aq) $\to$ Zn(s)+ 2 Fe³⁺(aq)
If [Zn²⁺] = 1.50 $\times$ 10^-4 M,[Fe³⁺] = 0.0200 M,and [Fe²⁺] = 0.0100 M.The standard reduction potentials are as follows:
Zn²⁺(aq)+ 2 e^- $\to$ Zn(s) $~~~~~~~~$ E ^$\circ$ = -0.763 V
Fe³⁺(aq)+ e^- $\to$ Fe²⁺(aq) $~~~~~~~~$ E ^$\circ$ = +0.771 V

A) -1.665 V
B) -1.534 V
C) -1.439 V
D) -0.008 V
E) +0.008 V

Question 52

The cell potential of the following electrochemical cell is determined using an unspecified concentration of acid.What is the pH of the acid solution given that the measured cell potential is -0.558 V and the anode reduction potential (E ^$\circ$ is 0.222 V at 25 ^$\circ$ C?
Ag(s)| AgCl(s)| Cl^-(aq,1.0 M)|| H⁺(aq,? M)| H₂(g,1.0 atm)| Pt(s)

A) 5.68
B) 13.2
C) 6.18
D) 11.4
E) 1.32

Question 53

For the cell reaction l )
The standard cell potential is 1.34 V.To determine the cell potential at nonstandard conditions,what is the value that should be used for n in the Nernst equation?

A) 8
B) 10
C) 5
D) 2
E) 6

Question 54

Calculate E°_cell for the cell for the reaction below,
2Cr(s)+ 3Sn⁴⁺(aq) $\to$ 3Sn²⁺(aq)+2Cr³⁺(aq)
Given the following standard reduction potentials.
Cr³⁺(aq)+ 3e^- $\to$ Cr(s) $~~~~~~~~$$~~~~~~~~$ E ^$\circ$ = -0.74 V
Sn⁴⁺(aq)+ 2e^- $\to$ Sn²⁺(aq) $~~~~~~~~$$~ ~~$ E ^$\circ$ = 0.15V

A) 0.89 V
B) 0.59 V
C) 0.42 V
D) -0.59 V
E) (-0.89) V

Question 55

What is the standard cell potential ( )for the following below,
2Ag(s)+ Pb²⁺(aq) $\to$ 2Ag⁺(aq)+ Pb(s)
Given the following standard reduction potentials.
Ag⁺(aq)+ e^- $\to$ Ag(s) $~~~~~~~~$$~~~~~~~~$ E ^$\circ$ =0.8 V
Pb²⁺(aq)+2e^- $\to$ Pb(s) $~~~~~~~~$$~~~~~~~~$ E ^$\circ$ =-0.126 V

A) -0.926 V
B) 0.926 V
C) -1.726 V
D) 1.726 V
E) 1.474 V

Question 56

Calculate E_cell for the following electrochemical cell at 25 ^$\circ$ C
Pt(s)| Fe³⁺(aq,0.100 M),Fe²⁺(aq,0.040 M)|| Cl^-(aq,0.50 M)| AgCl(s)| Ag(s)
Given the following standard reduction potentials.
AgCl(s)+ e^- $\to$ Ag(s)+ Cl^-(aq) $~~~~~~~~$ E ^$\circ$ = +0.222 V
Fe³⁺(aq)+ e^- $\to$ Fe²⁺(aq) $~~~~~~~~$$~~~~~~~~$ E ^$\circ$ = +0.771 V

A) -1.034 V
B) -0.590 V
C) -0.508 V
D) -0.555 V
E) +1.034 V

Question 57

Which of the following statements is true concerning the electrochemical cell below,
Ba(s)| Ba²⁺(aq,1.0 M)|| Mn²⁺(aq,1.0 M)| Mn(s)
And given the following standard reduction potentials?
Ba²⁺(aq)+ 2e^- $\to$ Ba(s); $~~~~~~~~$$~~~~~~~~$ E° = -2.91 V
Mn²⁺(aq)+ 2e^- $\to$ Mn(s); $~~~~~~~~$$~~~~~~~~$ E° = -1.19 V

A) The cell reaction is spontaneous with a standard cell potential of -4.10 V.
B) The cell reaction is spontaneous with a standard cell potential of 1.72 V.
C) The cell reaction is nonspontaneous with a standard cell potential of 1.72 V.
D) The cell reaction is nonspontaneous with a standard cell potential of -4.10 V.
E) The cell reaction is spontaneous with a standard cell potential of -1.72 V.

Question 58

What is the value of the reaction quotient,Q,for the voltaic cell constructed from the following two half-reactions when the Zn²⁺ concentration is 0.0120 M and the Ag⁺ concentration is 1.25 M?

A) 9.60 $\times$ 10^-3
B) 7.68 $\times$ 10^-3
C) 104
D) 1.25 $\times$ 10^-2
E) 130

Question 59

Which of the following equations is a correct form of the Nernst equation?

A)
B)
C)
D)
E)

Question 60

Calculate E_cell for the following electrochemical cell at 25 ^$\circ$ C
Pt(s)| H₂(g,1.00 atm)| H⁺(aq,1.00 M)|| Sn²⁺(aq,0.350 M),Sn⁴⁺(aq,0.020 M)| Pt(s)
Given the following standard reduction potentials.
Sn⁴⁺(aq)+ 2 e^- $\to$ Sn²⁺(s) $~~~~~~~~$ E ^$\circ$ = +0.15 V
2 H⁺(aq)+ 2 e^- $\to$ H₂(g) $~~~~~~~~$ E ^$\circ$ = 0.00 V

A) -0.19 V
B) +0.08 V
C) +0.11 V
D) +0.19 V
E) +0.22 V

Question 61

Given the following standard reduction potentials,
Pb²⁺(aq)+ 2 e^- $\to$ Pb(s) $~~~~~~~~$$~~~~~~~~$$~~~~~~~~$ E ^$\circ$ = -0.126 V
PbSO₄(s)+ 2 e^- $\to$ Pb(s)+ SO₄^2-(aq) $~~~~~~~~$ E ^$\circ$ = -0.355 V
Determine K_sp for PbSO₄(s)at 25 ^$\circ$ C.

A) 3.4 $\times$ 10^-28
B) 1.8 $\times$ 10^-8
C) 5.6 $\times$ 10^-5
D) 5.6 $\times$ 10⁷
E) 2.9 $\times$ 10³⁷

Question 62

What charge,in coulombs,is required to deposit 1.5 g Mg(s)from a solution of Mg²⁺(aq)?

A) 4.1 $\times$ 10² C
B) 6.0 $\times$ 10³ C
C) 1.2 $\times$ 10⁴ C
D) 2.9 $\times$ 10⁵ C
E) 3.1 $\times$ 10⁶ C

Question 63

One kind of battery used in watches contains mercury(II)oxide.As current flows,the mercury(II)oxide is reduced to mercury.
HgO(s)+ H₂O( )+ 2 e^- $\to$ Hg( )+ 2 OH^-(aq)
If 2.3 $\times$ 10^-5 amperes flows continuously for 1200 days,what mass of Hg(
)is produced?

A) 2.5 g
B) 5.0 g
C) 9.9 g
D) 13 g
E) 15 g

Question 64

What mass of chromium could be deposited by electrolysis of an aqueous solution of Cr₂(SO₄)₃ for 160 min using a constant current of 15.0 A? Assume 100% current efficiency.(F = 96485 C/mol)

A) 0.431 g
B) 25.9 g
C) 232.8 g
D) 0.187 g
E) 38.8 g

Question 65

If $\Delta$ _rG ^$\circ$ for the following reaction is -22.2 kJ/mol-rxn,calculate .
Cu²⁺(aq)+ 2 Ag(s)+ 2 Cl^-(aq) $\to$ Cu(s)+ 2 AgCl(s)

A) -0.460 V
B) -0.115 V
C) +0.115 V
D) +0.230 V
E) +0.559 V

Question 66

When an aqueous solution of sodium sulfate is electrolyzed,what are the expected products?
Reduction Half-Reaction $~~~~~~~~$$~~~~~~~~$ E° (V)

$\to$ Na(s) $~~~~~~~~$$~~~~~~~~$$~~~~~~~~$ -2.71

2H₂O(l)+ 2e^- $\to$ H₂(g)+ 2OH^-(aq) $~~~~ ~~$$~ ~$ -0.83

2H⁺(aq)+ 2e^- $\to$ H₂(g) $~~~~~~~~$$~~~~~~~~$$~~~~~~~~$ 0.00

O₂(g)+ 4H⁺(aq)+ 4e^- $\to$ 2H₂O(l) $~~~~~~~~$$~~ ~$ 1.23

S₂O₈^2-(aq)+ 2e^- $\to$ 2SO₄^2-(aq) $~~~~~~~~$$~~~~~~ ~$ 2.01

A) Na(s)and H₂(g)
B) H₂(g),OH^-(aq),O₂(g),and H⁺(aq)
C) O₂(g),H⁺(aq),and Na(s)
D) H₂(g),OH^-(aq),and Na(s)
E) H₂(g),OH^-(aq),and S₂O₈^2-(aq)

Question 67

The standard cell potential of the following electrochemical cell is 0.19 V.Pt | Sn⁴⁺(aq,1.0 M),Sn²⁺(aq,1.0 M)|| Cu²⁺(aq,0.200 M)| Cu
Which factor will increase the measured cell potential of the galvanic cell?

A) switching from a platinum to a graphite anode
B) increasing the size of the anode
C) decreasing the concentration of Cu²⁺
D) increasing the concentration of Sn⁴⁺
E) decreasing the temperature of the cell

Question 68

What half-reaction occurs at the cathode during the electrolysis of molten potassium bromide?

A) K(s) $\to$ K⁺( $\ell$ )+ e^-
B) Br₂( $\ell$ )+ 2e^- $\to$ 2Br^-( $\ell$ )
C) 2Br^-( $\ell$ ) $\to$ Br₂( $\ell$ )+ 2e^-
D) K⁺( $\ell$ )+ e^- $\to$ K(s)
E) 2H₂O( $\ell$ )+ 2e^- $\to$ H₂(g)+ 2OH^-(( $\ell$ )

Question 69

In an electrolytic cell,reduction occurs at the ________ and oxidation occurs at the ________.

Question 70

If the value of E°_cell is for the reaction
What is the value of E°_cell for
½ Cl₂(g)?

A)
B)
C)
D)
E)

Question 71

How many moles of electrons are produced from a current of 14.4 A in 3.20 hours?

A) 4.78 $\times$ 10^-4 mol
B) 1.72 mol
C) 46.1 mol
D) 3.35 mol
E) 9.33 $\times$ 10³ mol

Question 72

Calculate the equilibrium constant for the following reaction at 25 ^$\circ$ C,
2 IO₃^-(aq)+ 5 Hg( )+ 12 H⁺(aq) $\to$ I₂(s)+ 5 Hg²⁺(aq)+ 6 H₂O( )
Given the following thermodynamic information.
IO₃^-(aq)+ 6 H⁺(aq)+ 5 e^- $\to$ I₂(s)+ 3 H₂O( ) $~~~~~~~~$ E ^$\circ$ = +1.20 V
Hg²⁺(aq)+ 2 e^- $\to$ Hg( ) $~~~~~~~~$$~~~~~~~~$$~~~~~~~~$$~~~~~~~~$ E ^$\circ$ = +0.86 V

A) 3 $\times$ 10^-58
B) 6 $\times$ 10⁵
C) 3 $\times$ 10¹¹
D) 6 $\times$ 10²⁸
E) 3 $\times$ 10⁵⁷

Question 73

Which of the following is true for a reaction that is spontaneous as written?

A) ( $\Delta$ _rG ^$\circ$ ) < 0; E ^$\circ$ _cell > 0
B) ( $\Delta$ _rG ^$\circ$ ) > 0; E ^$\circ$ _cell < 0
C) ( $\Delta$ _rG ^$\circ$ ) < 0; E ^$\circ$ _cell < 0
D) ( $\Delta$ _rG ^$\circ$ ) > 0; E ^$\circ$ _cell > 0
E) ( $\Delta$ _rG ^$\circ$ ) > 0; E ^$\circ$ _cell = 0

Question 74

A current of 15.0 A is passed through molten magnesium chloride for 15.0 h.How many moles of magnesium metal could be produced via this electrolysis?

A) 0.0700 mol
B) 4.20 mol
C) 0.37 mol
D) 0.22 mol
E) 8.40 mol

Question 75

Given: $\to$
$~~~~~~~~$$\to$
What is the standard Gibbs free-energy change for the following reaction?

A)
B)
C)
D)
E)

Question 76

Calculate $\Delta$ _rG ^$\circ$ for the disproportionation reaction of Cu⁺ at 25 ^$\circ$ C,
2 Cu⁺(aq) $\to$ Cu²⁺(aq)+ Cu(s)
Given the following thermodynamic information.
Cu⁺(aq)+ e^- $\to$ Cu(s) $~~~~~~~~$ E ^$\circ$ = +0.518 V
Cu²⁺(aq)+ 2 e^- $\to$ Cu(s) $~~~~~~~~$ E ^$\circ$ = +0.337 V

A) -165 kJ/mol.rxn
B) -135 kJ/mol.rxn
C) -34.9 kJ/mol.rxn
D) +17.5 kJ/mol.rxn
E) +135 kJ/mol.rxn

Question 77

What is the equilibrium constant (K)at 25°C for the following cell reaction?

A) 0.014
B) 1.7
C) 0.40
D) 1.0
E) 3.0

Question 78

Al³⁺ is reduced to Al(s)at an electrode.If a current of 2.75 ampere is passed for 36 hours,what mass of aluminum is deposited at the electrode? Assume 100% current efficiency.

A) 9.2 $\times$ 10^-3 g
B) 3.3 $\times$ 10¹ g
C) 9.9 $\times$ 10¹ g
D) 1.0 $\times$ 10² g
E) 3.0 $\times$ 10² g

Question 79

Calculate the equilibrium constant for the reaction below at 25 ^$\circ$ C,
Co(s)+ 2 Cr³⁺(aq) $\to$ Co²⁺(aq)+ 2 Cr²⁺(aq)
Given the following thermodynamic information.
Co²⁺(aq)+ 2 e^- $\to$ Co(s) $~~~~~~~~$ E ^$\circ$ = -0.28 V
Cr³⁺(aq)+ e^- $\to$ Cr²⁺(aq) $~~~~~~~~$ E ^$\circ$ = -0.41 V

A) 4.0 $\times$ 10^-5
B) 2.5 $\times$ 10⁴
C) 1.0 $\times$ 10⁵
D) 1.2 $\times$ 10⁵
E) 1.3 $\times$ 10⁵

Question 80

Calculate the standard reduction potential for the following reaction at 25 ^$\circ$ C,
AuCl₄^-(aq)+ 3 e^- $\to$ Au(s)+ 4 Cl^-(aq)
Given the following thermodynamic information.
Au³⁺(aq)+ 3 e^- $\to$ Au(s) $~~~~~~~~$$~~~~~~~~$$~~~~ ~~$ E ^$\circ$ = +1.50 V
Au³⁺(aq)+ 4 Cl^-(aq) $\to$ AuCl₄^-(aq) $~~~~~~~~$ K_f = 2.3 $\times$ 10²⁵

A) -1.28 V
B) -0.50 V
C) +1.00 V
D) +1.28 V
E) +3.85 V