Deck 21: Electrochemistry: Chemical Change and Electrical Work

Question 1

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

A)The anode will definitely gain weight in a voltaic cell.
B)Oxidation occurs at the cathode of both cells.
C)The free energy change, $\Delta$ G,is negative for the voltaic cell.
D)The electrons in the external wire flow from cathode to anode in an electrolytic cell.
E)None of these statements is correct.

Answer 1

The free energy change, $\Delta$ G,is negative for the voltaic cell.

Question 2

When the following redox equation is balanced with smallest whole number coefficients,the coefficient for the hydrogen sulfate ion will be ______.
Al(s)+ HSO₄^-(aq)+ OH^-(aq) $\to$ Al₂O₃(s)+ S^2-(aq)+ H₂O(l)

A)1
B)3
C)4
D)8
E)None of these choices is correct.

Answer 2

3

Question 3

When the following redox equation is balanced with smallest whole number coefficients,the coefficient for nitrogen dioxide will be _____.
I₂(s)+ HNO₃(aq) $\to$ HIO₃(aq)+ NO₂(g)+ H₂O(l)

A)1
B)2
C)4
D)10
E)None of these choices is correct.

Answer 3

10

Question 4

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

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 N₂(g)is the reducing agent.

Question 5

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

A)CuO and H₂
B)H₂ and CuO
C)CuO and Cu
D)H₂O and H₂
E)None of these choices is correct.

Question 6

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?

A)2I^-(aq)+ Zn²⁺(aq) $\to$ I₂(s)+ Zn(s)
B)I₂(s)+ Zn(s) $\to$ 2I^-(aq)+ Zn²⁺(aq)
C)2I^-(aq)+ Zn(s) $\to$ I₂(s)+ Zn²⁺(aq)
D)I₂(s)+ Zn²⁺(aq) $\to$ 2I^-(aq)+ Zn(s)
E)None of these,since graphite must be in the equation.

Question 7

Consider the following redox equation
Mn(OH)₂(s)+ MnO₄^-(aq) $\to$ MnO₄^2-(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?

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

Question 8

Consider the following balanced redox reaction
Mn²⁺(aq)+ S₂O₈^2-(aq)+ 2H₂O(l) $\to$ MnO₂(s)+ 4H⁺(aq)+ 2SO₄^2-(aq)
Which of the following statements is true?

A)Mn²⁺(aq)is the oxidizing agent and is reduced.
B)Mn²⁺(aq)is the oxidizing agent and is oxidized.
C)Mn²⁺(aq)is the reducing agent and is oxidized.
D)Mn²⁺(aq)is the reducing agent and is reduced.
E)Manganese does not change its oxidation number in this reaction.

Question 9

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

A)zinc
B)graphite
C)copper
D)iron
E)sodium

Question 10

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

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, $\Delta$ 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 11

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)?

A)HCl and Cl^-
B)H⁺ and OH^-
C)H₂O and H⁺
D)Fe³⁺ and Fe₂O₃
E)MnO₂ and Mn²⁺

Question 12

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 reactions occurs at the anode?

A)Al(s) $\to$ Al³⁺(aq)+ 3e^-
B)Al³⁺(aq)+ 3e $\to$ Al(s)
C)Ni(s) $\to$ Ni²⁺(aq)+ 2e^-
D)Ni²⁺(aq)+ 2e^- $\to$ Ni(s)
E)None of these choices are correct.

Question 13

When the following redox equation is balanced with smallest whole number coefficients,the coefficient for zinc will be _____.
Zn(s)+ ReO₄^-(aq) $\to$ Re(s)+ Zn²⁺(aq)(acidic solution)

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

Question 14

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)Ni²⁺(aq)+ Al(s) $\to$ Al³⁺(aq)+ Ni(s)
B)3Ni²⁺(aq)+ 2Al(s) $\to$ 2Al³⁺(aq)+ 3Ni(s)
C)Ni(s)+ Al³⁺(aq) $\to$ Ni²⁺(aq)+ Al(s)
D)3Ni(s)+ 2Al³⁺(aq) $\to$ 3Ni²⁺(aq)+ 2Al(s)
E)None of these choices is correct.

Question 15

A voltaic cell is prepared using copper and silver.Its cell notation is shown below.
Cu(s)| Cu²⁺(aq)|| Ag⁺(aq)| Ag(s)
Which of the following processes occurs at the cathode?

A)Cu(s) $\to$ Cu²⁺(aq)+ 2e^-
B)Cu²⁺(aq)+ 2e^- $\to$ Cu(s)
C)Ag(s) $\to$ Ag⁺(aq)+ e^-
D)Ag⁺(aq)+ e^- $\to$ Ag(s)
E)Cu(s)+ 2Ag⁺(aq) $\to$ Cu²⁺(aq)+ 2Ag(s)

Question 16

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

Question 17

Which component of the following cell notation is the anode?
P | Q || R | S

A)P
B)Q
C)R
D)S
E)One of the | symbols is the anode.

Question 18

When the following redox equation is balanced with smallest whole number coefficients,the coefficient for the iodide ion will be _____.
I^-(aq)+ NO₃^-(aq) $\to$ NO(g)+ I₂(s)(acidic solution)

A)2
B)3
C)6
D)8
E)None of these choices is correct.

Question 19

When the following redox equation is balanced with smallest whole number coefficients,the coefficient for Sn(OH)₃^- will be _____.
Bi(OH)₃(s)+ Sn(OH)₃^-(aq) $\to$ Sn(OH)₆^2-(aq)+ Bi(s)(basic solution)

A)1
B)2
C)3
D)6
E)None of these choices is correct.

Question 20

Which one of the following is not a redox reaction?

A)Al(OH)₄^-(aq)+ 4H⁺(aq) $\to$ Al³⁺(aq)+ 4H₂O(l)
B)C₆H₁₂O₆(s)+ 6O₂(g) $\to$ 6CO₂(g)+ 6H₂O(l)
C)Na₆FeCl₈(s)+ 2Na(l) $\to$ 8NaCl(s)+ Fe(s)
D)2H₂O₂(aq) $\to$ 2H₂O(l)+ O₂(g)
E)CO₂(g)+ H₂(g) $\to$ CO(g)+ H₂O(g)

Question 21

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) $\to$ MnO₂(s)+ 3Co³⁺(aq)+ 4OH^-(aq)

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 22

What is the E°_cell for the cell represented by the combination of the following half-reactions?
ClO₄^-(aq)+ 8H⁺(aq)+ 8e^-
Cl^-(aq)+ 4H₂O(l);E° = 1.389 V
VO₂⁺(aq)+ 2H⁺(aq)+ e^-
VO⁺(aq)+ H₂O(l);E° = 0.991 V

A)-0.398 V
B)-2.380 V
C)0.398 V
D)2.380 V
E)None of these choices is correct.

Question 23

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?

A)C(s)+ 2H⁺(aq) $\to$ H₂(g)+ C²⁺(aq)
B)C(s)+ A²⁺(aq) $\to$ A(s)+ C²⁺(aq)
C)B(s)+ C²⁺(aq) $\to$ C(s)+ B²⁺(aq)
D)A(s)+ 2H⁺(aq) $\to$ H₂(g)+ A²⁺(aq)
E)B(s)+ 2H⁺(aq) $\to$ H₂(g)+ B²⁺(aq)

Question 24

The voltaic cell made up of cobalt,copper and their M²⁺ ions,has E°_cell = 0.62 V.If E° of the cathode half-cell is 0.34 V,what is E° of the anode half-cell?
Cu²⁺(aq)+ Co(s) $\to$ Cu(s)+ Co²⁺(aq)

A)-0.28 V
B)-0.96V
C)0.28 V
D)0.96 V
E)None of these choices is correct.

Question 25

Examine the following half-reactions and select the weakest reducing agent among the substances.
Cr(OH)₃(s)+ 3e^-
Cr(s)+ 3OH^-(aq);E° = -1.48 V
SnO₂(s)+ 2H₂O(l)+ 4e^-
Sn(s)+ 4OH^-(aq);E° = -0.945 V
MnO₂(s)+ 4H⁺(aq)+ 2e^-
Mn²⁺(aq)+ 2H₂O(l);E° = 1.224 V
Hg₂SO₄(s)+ 2e^-
2Hg(l)+ SO₄^2-(aq);E° = 0.613 V

A)Cr(s)
B)Sn(s)
C)Mn²⁺(aq)
D)Hg(l)
E)OH^-(aq)

Question 26

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

Question 27

A cell can be prepared from copper and tin.What is the E°_cell for the cell that forms from the following half-reactions?
Cu²⁺(aq)+ 2e^-
Cu(s);E° = 0.34 V
Sn⁴⁺(aq)+ 2e^-
Sn²⁺(aq);E° = 0.13 V

A)0.47 V
B)0.21 V
C)-0.21 V
D)-0.47 V
E)0.42 V

Question 28

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

A)Cr²⁺(aq)
B)Fe(s)
C)Fe²⁺(aq)
D)Sr²⁺(aq)
E)Co²⁺(aq)

Question 29

The redox reaction of peroxydisulfate with iodide has been used for many years as part of the iodine clock reaction which introduces students to kinetics.If E°_cell = 1.587 V and E° of the cathode half-cell is 0.536 V,what is E° of the anode half-cell?
S₂O₈^2-(aq)+ 2H⁺ + 2I^-(aq) $\to$ 2HSO₄^-(aq)+ I₂(aq)

A)-1.051 V
B)-2.123 V
C)1.051 V
D)2.123 V
E)None of these choices is correct.

Question 30

A battery is considered "dead" when

A)Q < 1
B)Q = 1
C)Q > 1
D)Q = K
E)Q/K= 0

Question 31

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) $\to$ 2Cr³⁺(aq)+ (aq)+ 6I^-(aq)

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 32

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

A)Hg(l)
B)Zn(s)
C)Ag(s)
D)BH₄^-(aq)
E)Zn(OH)₂(s)

Question 33

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

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

Question 34

What is the value of the equilibrium constant for the cell reaction below at 25°C? E°_cell = 0.30 V
Sn²⁺(aq)+ Fe(s)
Sn(s)+ Fe²⁺(aq)

A)1.2 $\times$ 10⁵
B)1.4 $\times$ 10¹⁰
C)8.6 $\times$ 10^-6
D)7.1 $\times$ 10^-11
E)2.3 $\times$ 10²³

Question 35

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
FeO₄^2-(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

A)[PtCl₄]^2-(aq)
B)RuO₄(s)
C)HFeO₄^- (aq)
D)H₄XeO₆(aq)
E)Cl^-(aq)

Question 36

Calculate E°_cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous.
H₂O₂(aq)+ 2H⁺(aq)+ 2e^-
2H₂O(l);E° = 1.77 V
Fe³⁺ (aq)+ e^-
Fe²⁺(aq);E° = 0.77 V
Overall reaction:
2Fe³⁺(aq)+ 2H₂O(l) $\to$ H₂O₂(aq)+ 2H⁺(aq)+ 2Fe²⁺(aq)

A)E°_cell = -1.00 V,nonspontaneous
B)E°_cell = -1.00 V,spontaneous
C)E°_cell = 1.00 V,nonspontaneous
D)E°_cell = 1.00 V,spontaneous
E)E°_cell = -0.23 V,nonspontaneous

Question 37

Examine the following half-reactions and select the weakest oxidizing agent among the species listed.
AuBr₄^-(aq)+ 3e^-
Au(s)+ 4Br^-(aq);E° = 0.854 V
Mn²⁺(aq)+ 2e^-
Mn(s);E° = -1.185 V
K⁺(aq)+ e^-
K(s);E° = -2.931 V
F₂O(aq)+ 2H⁺(aq)+ 4e^-
2F^-(aq)+ H₂O(l);E° = 2.153 V

A)AuBr₄^-(aq)
B)Mn²⁺(aq)
C)K⁺(aq)
D)F₂O(aq)
E)H⁺(aq)

Question 38

Examine the following half-reactions and select the strongest reducing agent among the species listed.
PbI₂(s)+ 2e^-
Pb(s)+ 2I^-(aq);E° = -0.365 V
Ca²⁺(aq)+ 2e^-
Ca(s);E° = -2.868 V
Pt²⁺(aq)+ 2e^-
Pt(s);E° = 1.18 V
Br₂(l)+ 2e^-
2Br^-(aq);E° = 1.066 V

A)Pb(s)
B)Ca(s)
C)Pt(s)
D)Br^-(aq)
E)Pt²⁺(aq)

Question 39

Calculate E°_cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous.
O₂(g)+ 4H⁺(aq)+ 4e^-
2H₂O(l);E° = 1.229 V
Al³⁺(aq)+ 3e^-
Al(s);E° = -1.662 V
Overall reaction:
4Al(s)+ 3O₂(g)+ 12H⁺(aq) $\to$ 4Al³⁺(aq)+ 6H₂O(l)

A)E°_cell = -2.891 V,nonspontaneous
B)E°_cell = -2.891 V,spontaneous
C)E°_cell = 2.891 V,nonspontaneous
D)E°_cell = 2.891 V,spontaneous
E)Spontaneous,but none of these values of E°_cell is correct.

Question 40

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

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 41

A concentration cell consists of two Al/Al³⁺electrodes.The electrolyte in compartment A is 0.050 M Al(NO₃)₃ and in compartment B is 1.25 M Al(NO₃)₃.What is the voltage of the cell at 25°C?

A)0.083 V
B)0.062 V
C)0.041V
D)0.028 V
E)None of these choices is correct.

Question 42

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.

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

Question 43

Calculate $\Delta$ G° for the reaction of iron(II)ions with one mole of permanganate ions.
MnO₄^-(aq)+ 8H⁺(aq)+ 5e^-
Mn²⁺(aq)+ 4H₂O(l);E° = 1.51 V
Fe³⁺(aq)+ e^-
Fe²⁺(aq);E°= 0.77 V

A)-71.4 kJ
B)-286 kJ
C)-357 kJ
D)-428 kJ
E)None of these choices is correct.

Question 44

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

Question 45

The following half-reactions occur in the mercury battery used in calculators.If E°_cell = 1.357 V,calculate the equilibrium constant for the cell reaction at 25°C.(Assume the stoichiometric coefficients in the cell reaction are all equal to 1. )
HgO(s)+ H₂O(l)+ 2e^-
Hg(l)+ 2OH^-(aq)
ZnO(s)+ H₂O(l)+ 2e^-
Zn(s)+ 2OH^-(aq)

A)9.4 $\times$ 10²²
B)7.5 $\times$ 10⁴⁵
C)6.4 $\times$ 10⁶³
D)7.8 $\times$ 10⁹¹
E)> 9.9 $\times$ 10⁹⁹

Question 46

Consider the non-aqueous cell reaction
2Na(l)+ FeCl₂(s)
2NaCl(s)+ Fe(s)
For which E°_cell = 2.35 V at 200°C. $\Delta$ G° at this temperature is

A)453 kJ
B)-453 kJ
C)907 kJ
D)-907 kJ
E)None of these choices is correct.

Question 47

Consider the reaction of iodine with manganese dioxide
3I₂(s)+ 2MnO₂(s)+ 8OH^-(aq)
6I^-(aq)+ 2MnO₄^-(aq)+ 4H₂O(l)
The equilibrium constant for the overall reaction is 8.30 $\times$ 10^-7.Calculate $\Delta$ G° for the reaction at 25°C.

A)-15.1 kJ
B)-34.7 kJ
C)15.1 kJ
D)34.7 kJ
E)None of these choices is correct.

Question 48

A battery that cannot be recharged is a

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

Question 49

Consider the reaction of iodine with manganese dioxide
3I₂(s)+ 2MnO₂(s)+ 8OH^-(aq)
6I^-(aq)+ 2MnO₄^-(aq)+ 4H₂O(l)
The equilibrium constant for the overall reaction is 8.30 $\times$ 10^-7.Calculate E°_cell for the reaction at 25°C.

A)-0.36 V
B)-0.18 V
C)-0.12 V
D)-0.060 V
E)None of these choices is correct.

Question 50

A voltaic cell consists of a Cd/Cd²⁺ electrode (E° = -0.40 V)and a Fe/Fe²⁺ electrode (E°= -0.44 V).If E_cell = 0 and the temperature is 25°C,what is the ratio [Fe²⁺]/[Cd²⁺]?

A)2 $\times$ 10¹
B)1 $\times$ 10¹
C)1
D)1 $\times$ 10^-1
E)5 $\times$ 10^-2

Question 51

The value of the equilibrium constant for the reaction of nickel(II)ions with cadmium metal is 1.17 $\times$ 10⁵.Calculate $\Delta$ G° for the reaction at 25°C.

A)-12.6 kJ
B)-28.9 kJ
C)12.6 kJ
D)28.9 kJ
E)None of these choices is correct.

Question 52

Calculate $\Delta$ G° 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

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

Question 53

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.

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

Question 54

The value of E°_cell for the reaction
2Cr³⁺(aq)+ 6Hg(l) $\to$ 2Cr(s)+ 3Hg₂²⁺(aq)
Is 1.59 V.Calculate $\Delta$ G° for the reaction.

A)-921 kJ
B)-767 kJ
C)-460 kJ
D)-307 kJ
E)None of these choices is correct.

Question 55

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

Question 56

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. )

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

Question 57

A concentration cell consists of two Zn/Zn²⁺ electrodes.The electrolyte in compartment A is 0.10 M Zn(NO₃)₂ and in compartment B is 0.60 M Zn(NO₃)₂.What is the voltage of the cell at 25°C?

A)0.010 V
B)0.020 V
C)0.023 V
D)0.046 V
E)None of these choices is correct.

Question 58

Consider the reaction in the lead-acid cell
Pb(s)+ PbO₂(s)+ 2H₂SO₄(aq) $\to$ 2PbSO₄(aq)+ 2H₂O(l)
For which E°_cell = 2.04 V at 298 K. $\Delta$ G° for this reaction is

A)-3.94 $\times$ 10⁵ kJ
B)-3.94 $\times$ 10² kJ
C)-1.97 $\times$ 10⁵ kJ
D)-7.87 $\times$ 10² kJ
E)None of these choices is correct.

Question 59

Calculate E°_cell for the reaction of nickel(II)ions with cadmium metal at 25°C.K = 1.17 $\times$ 10⁵
Ni²⁺(aq)+ Cd(s) $\to$ Cd²⁺(aq)+ Ni(s)

A)0.075 V
B)0.10 V
C)0.12 V
D)0.15 V
E)0.30 V

Question 60

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)4.1 $\times$ 10²⁰
B)8.2 $\times$ 10³⁰
C)3.3 $\times$ 10⁵¹
D)7.4 $\times$ 10⁶¹
E)> 9.9 $\times$ 10⁹⁹

Question 61

In one or two short sentences each,explain what is meant by the following terms.
a.galvanic or voltaic cell
b.electrolytic cell
c.salt bridge
d.secondary battery or cell
e.primary battery or cell
f.glass electrode

Question 62

Two cells are connected in series,so that the same current flows through two electrodes where the following half-reactions occur
Cu²⁺(aq)+ 2e^- $\to$ Cu(s)and Ag⁺(aq)+ e^- $\to$ Ag(s)
For every 1.00 g of copper produced in the first process,how many grams of silver will be produced in the second one?

A)0.294 g
B)0.588 g
C)0.850 g
D)1.70 g
E)3.40 g

Question 63

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

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

Question 64

A concentration cell is based on the aqueous reaction
Cu²⁺(1.00 M) $\to$ Cu²⁺(0.0100 M)
The cell consists of copper electrodes dipping into solutions of Cu²⁺ ions.The anions present are sulfate ions.Write the shorthand cell notation for this cell.

Question 65

The Downs cell is used in the electrolysis of

A)molten calcium chloride.
B)aqueous calcium chloride.
C)molten sodium chloride.
D)aqueous sodium chloride.
E)None of the above.

Question 66

A concentration cell is based on the aqueous reaction
Cu²⁺(1.00 M) $\to$ Cu²⁺(0.0100 M)
The cell consists of copper electrodes dipping into solutions of Cu²⁺ ions.The anions present are sulfate ions.Draw a neat diagram to represent this cell,showing and labeling all necessary components including: anode,cathode,electron flow,cation flow and anion flow.

Question 67

Write down equations representing the anode half-reaction,the cathode half-reaction and the overall cell reaction for the lead-acid battery.

Question 68

Which,if any,of the following metals would not be capable of acting as a sacrificial anode when used with iron E°_Fe = -0.44 V;all E° values refer to the M²⁺/M half-cell reactions.

A)manganese,Mn,E° = -1.18 V
B)cadmium,Cd,E° = -0.40 V
C)magnesium,Mg,E° = -2.37 V
D)zinc,Zn,E° = -0.76 V
E)All of these metals are capable of acting as sacrificial anodes with iron.

Question 69

How many grams of oxygen gas will be produced in the electrolysis of water,for every gram of hydrogen gas formed?
Reaction: 2H₂O(l) $\to$ 2H₂(g)+ O₂(g)

A)31.7 g
B)15.9 g
C)7.94 g
D)3.97 g
E)1.98 g

Question 70

A current of 250.A flows for 24.0 hours at an anode where the reaction occurring is
Mn²⁺(aq)+ 2H₂O(l) $\to$ MnO₂(s)+ 4H⁺(aq)+ 2e^-
What mass of MnO₂ is deposited at this anode?

A)19.5 kg
B)12.9 kg
C)4.87 kg
D)2.43 kg
E)None of these choices is correct.

Question 71

A much-studied cell in electrochemistry has the following cell notation:
Ag(s)| AgCl(s)| HCl(aq)| H₂(g)| Pt(s)
Bearing in mind that HCl(aq)consists of H⁺(aq)and Cl^-(aq),and that this solution is in contact with both electrodes (there is no salt bridge),write down balanced equations for
a.the anode half-reaction.
b.the cathode half-reaction.
c.the cell reaction.

Question 72

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

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

Question 73

The chlor-alkali process produces chlorine,Cl₂(g),in large quantities.What other industrially important substances are produced in this process?

A)sodium and hydrogen
B)hydrogen and oxygen
C)sodium chloride and hydrogen
D)sodium and oxygen
E)sodium hydroxide and hydrogen

Question 74

Which,if any,of the following metals would be capable of acting as a sacrificial anode when used with iron pipe? E°_Fe = -0.44 V;all E° values refer to the M²⁺/M half-cell reactions.

A)copper,Cu,E° = 0.15 V
B)cobalt,Co,E° = -0.28 V
C)chromium,Cr,E° = -0.74 V
D)tin,Sn,E° = -0.14 V
E)None of these metals would be capable of acting as a sacrificial anode with iron.

Question 75

A concentration cell is based on the aqueous reaction
Cu²⁺(1.00 M) $\to$ Cu²⁺(0.0100 M)
Calculate the potential of this cell if it operates at 25.0°C.

Question 76

What product forms at the cathode during the electrolysis of molten NaCl in the Downs cell?

A)Na⁺(l)
B)Na(l)
C)Cl^-(l)
D)NaOH(aq)
E)Cl₂(g)

Question 77

A galvanic cell is constructed using the two hypothetical half-reactions
a.Write down the balanced equation representing the cell reaction.
b.Calculate the standard potential of this cell,E°_cell.
c.Calculate $\Delta$ G° for the cell reaction.

Question 78

Explain what is meant by a fuel cell.Provide a balanced equation to represent the reaction in any fuel cell of your choice.

Question 79

Cryolite,Na₃AlF₆ is used in the electrolysis of aluminum oxide because

A)it is a good source of fluoride ions.
B)it provides a source of fluorine,an oxidizing agent.
C)it provides a source of sodium,a reducing agent.
D)it reduces the energy requirement of the process,by lowering the melting point.
E)it is very soluble in water.

Question 80

A solution is prepared by dissolving 32.0 g of NiSO₄ in water.What current would be needed to deposit all of the nickel in 5.0 hours?

A)1.1 A
B)2.2 A
C)3.3 A
D)4.4 A
E)5.5 A