Prince George's Community College - Academic...

Prince George's Community CollegeCHM 1020 (Mr. Shah)

Electrochemistry Fall 2013

Part I Multiple Choices: Select the best answer and circle it. (100 points)

1. Which one of the following is not a redox reaction? A. Al(OH)4

-(aq) + 4H+(aq) Al3+(aq) + 4H2O(l)B. C6H12O6(s) + 6O2(g) 6CO2(g) + 6H2O(l)C. Na6FeCl8(s) + 2Na(l) 8NaCl(s) + Fe(s)D. 2H2O2(aq) 2H2O(l) + O2(g)E. CO2(g) + H2(g) CO(g) + H2O(g)

2. Consider the reaction

CuO(s) + H2(g) Cu(s) + H2O(l)

In this reaction, which substances are the oxidant and reductant, respectively? A. CuO and H2

B. H2 and CuOC. CuO and CuD. H2O and H2

E. None of these choices is correct.

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3. Consider the following balanced redox reaction

Mn2+(aq) + S2O82-(aq) + 2H2O(l) 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.

4. Consider the following balanced redox reaction

3CuO(s) + 2NH3(aq) 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.

5. When the following redox equation is balanced with smallest whole

number coefficients, the coefficient for nitrogen dioxide will be _____.

I2(s) + HNO3(aq) HIO3(aq) + NO2(g) + H2O(l) A. 1B. 2C. 4D. 10E. None of these choices is correct.

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6. 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) Al2O3(s) + S2-(aq) + H2O(l)

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


number coefficients, the coefficient for zinc will be _____.

Zn(s) + ReO4-(aq) Re(s) + Zn2+(aq) (acidic solution)



number coefficients, the coefficient for the iodide ion will be _____.

I-(aq) + NO3-(aq) NO(g) + I2(s) (acidic solution)


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9. 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) Sn(OH)6

2-(aq) + Bi(s) (basic solution) A. 1B. 2C. 3D. 6E. None of these choices is correct.

10.Consider the following redox equation

Mn(OH)2(s) + MnO4-(aq) 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 sideB. 4, product sideC. 6, reactant sideD. 6, product sideE. None of these choices is correct.

11.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, 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.

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12.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, 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.

13.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+

14.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.

15.Which of the following solids is commonly used as an inactive

electrode in electrochemical cells? A. zincB. graphiteC. copperD. ironE. sodium

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16.Which component of the following cell notation is the anode?

P | Q || R | S A. PB. QC. RD. SE. One of the | symbols is the anode.

17.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) Cu2+(aq) + 2e-

B. Cu2+(aq) + 2e- Cu(s)C. Ag(s) Ag+(aq) + e-

D. Ag+(aq) + e- Ag(s)E. Cu(s) + 2Ag+(aq) Cu2+(aq) + 2Ag(s)

18.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) Al3+(aq) + 3e-

B. Al3+(aq) + 3e Al(s)C. Ni(s) Ni2+(aq) + 2e-

D. Ni2+(aq) + 2e- Ni(s)E. None of these choices is correct.

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

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

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21.A cell can be prepared from copper and tin. What is the Ecell 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 VB. 0.21 VC. -0.21 VD. -0.47 VE. 0.42 V

22.What is the Ecell for the cell represented by the combination of the

following half-reactions? 2Hg2+(aq) + 2e- Hg2

2+(aq); E= 0.92 VCr3+ (aq) + 3e- Cr(s); E= -0.74 V A. -0.18 VB. 0.18 VC. 1.28 VD. 1.66 VE. 2.12 V

23.What is the Ecell for the cell represented by the combination of the

following half-reactions?

ClO4

-(aq) + 8H+(aq) + 8e- Cl-(aq) + 4H2O(l); E = 1.389 VVO2

+(aq) + 2H+(aq) + e- VO+(aq) + H2O(l); E = 0.991 V A. -0.398 VB. -2.380 VC. 0.398 VD. 2.380 VE. None of these choices is correct.

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24.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 Ecell= 1.587 V and E of the cathode half-cell is 0.536 V, what is E of the anode half-cell?

S2O82-(aq) + 2H+ + 2I-(aq) 2HSO4

-(aq) + I2(aq) A. -1.051 VB. -2.123 VC. 1.051 VD. 2.123 VE. None of these choices is correct.

25.The voltaic cell made up of cobalt, copper and their M2+ ions, has Ecell

= 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) Cu(s) + Co2+(aq) A. -0.28 VB. -0.96VC. 0.28 VD. 0.96 VE. None of these choices is correct.

26.Given that E for X + e- Y is greater than E for A + 2e- 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.

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27.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 VRuO4(s) + 8H+(aq) + 8e- Ru(s) + 4H2O(l); E = 1.038 VFeO4

2-(aq) + 8H+(aq) + 3e- Fe3+(aq) + 4H2O(l); E = 2.07 VH4XeO6(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)

28.Examine the following half-reactions and select the strongest

oxidizing agent among the species listed. Cr2+(aq) + 2e- Cr(s); E = -0.913 VFe2+(aq) + 2e- Fe(s); E = -0.447 VSr2+(aq) + 2e- Sr(s); E = -2.89 VCo2+(aq) + 2e- Co(s); E = -0.28 V A. Cr2+(aq)B. Fe(s)C. Fe2+(aq)D. Sr2+(aq)E. Co2+(aq)

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29.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 VK+(aq) + e- K(s); E = -2.931 VF2O(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)

30.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 VCa2+(aq) + 2e- Ca(s); E = -2.868 VPt2+(aq) + 2e- Pt(s); E = 1.18 VBr2(l) + 2e- 2Br-(aq); E = 1.066 V A. Pb(s)B. Ca(s)C. Pt(s)D. Br-(aq)E. Pt2+(aq)

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31.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 VZn(OH)2(s) + 2e- Zn(s) + 2OH-(aq); E = -1.25 VAg2O(s) + H2O(l) + 2e- Ag(s) + 2OH-(aq); E = 0.342 VB(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)

32.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 VSnO2(s) + 2H2O(l) + 4e- Sn(s) + 4OH-(aq); E = -0.945 VMnO2(s) + 4H+(aq) + 2e- Mn2+(aq) + 2H2O(l); E = 1.224 VHg2SO4(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)

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33.Calculate Ecell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. I2(s) + 2e- 2I-(aq); E = 0.53 VCr3+(aq) + 3e- Cr(s); E = -0.74 V

Overall reaction:

2Cr(s) + 3I2(s) 2Cr3+(aq) + (aq) + 6I-(aq) A. Ecell = -1.27 V, spontaneousB. Ecell = -1.27 V, nonspontaneousC. Ecell = 1.27 V, spontaneousD. Ecell = 1.27 V, nonspontaneousE. Ecell = 1.54 V, spontaneous

34.Calculate Ecell and indicate whether the overall reaction shown is

spontaneous or nonspontaneous. Co3+(aq) + e- Co2+(aq); E = 1.82 VMnO4

-(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. Ecell = -1.23 V, spontaneousB. Ecell = -1.23 V, nonspontaneousC. Ecell = 1.23 V, spontaneousD. Ecell = 1.23 V, nonspontaneousE. Ecell = -0.05 V, nonspontaneous

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35.Calculate Ecell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. O2(g) + 4H+(aq) + 4e- 2H2O(l); E = 1.229 VAl3+(aq) + 3e- Al(s); E = -1.662 V

Overall reaction:

4Al(s) + 3O2(g) + 12H+(aq) 4Al3+(aq) + 6H2O(l) A. Ecell = -2.891 V, nonspontaneousB. Ecell = -2.891 V, spontaneousC. Ecell = 2.891 V, nonspontaneousD. Ecell = 2.891 V, spontaneousE. Spontaneous, but none of these values of Ecell is correct.

36.Calculate Ecell and indicate whether the overall reaction shown is

spontaneous or nonspontaneous. H2O2(aq) + 2H+(aq) + 2e- 2H2O(l); E = 1.77 VFe3+ (aq) + e- Fe2+(aq); E = 0.77 V

Overall reaction:

2Fe3+(aq) + 2H2O(l) H2O2(aq) + 2H+(aq) + 2Fe2+(aq) A. Ecell = -1.00 V, nonspontaneousB. Ecell = -1.00 V, spontaneousC. Ecell = 1.00 V, nonspontaneousD. Ecell = 1.00 V, spontaneousE. Ecell = -0.23 V, nonspontaneous

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37.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) H2(g) + C2+(aq)B. C(s) + A2+(aq) A(s) + C2+(aq)C. B(s) + C2+(aq) C(s) + B2+(aq)D. A(s) + 2H+(aq) H2(g) + A2+(aq)E. B(s) + 2H+(aq) H2(g) + B2+(aq)

38.Which of the following conditions is most likely to apply to a fully-

charged secondary cell? A. Ecell = Ecell

B. Ecell = 0C. Q = 1D. Q < KE. Q = K

39.A battery is considered "dead" when

A. Q < 1B. Q = 1C. Q > 1D. Q = KE. Q/K = 0

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40.What is the value of the equilibrium constant for the cell reaction below at 25C? Ecell = 0.30 V

Sn2+(aq) + Fe(s) Sn(s) + Fe2+(aq) A. 1.2 105

B. 1.4 1010

C. 8.6 10-6

D. 7.1 10-11

E. 2.3 1023

Balance the following redox reaction in acidic solution.

1. Balance the following redox reaction in acidic solution.

Fe2+(aq) + MnO4-(aq) Fe3+(aq) + Mn2+(aq)


Cr2O72-(aq) + I-(aq) Cr3+(aq) + I2(s)

3. Balance the following redox reaction in basic solution.

MnO4-(aq) + C2O4

2-(aq) MnO2(s) + CO32-(aq)


MnO4-(aq) + I-(aq) MnO4

-2(s) + IO3-(aq)


MnO4-(aq) + CN-(aq) MnO2(s) + OCN-(aq)

Cell notation (line notation): A cell diagram shows the components of an electrochemical cell in a symbolic way. (Anode to cathode)

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Zn(s)|Zn++(aq) || Cu++(aq)|Cu(s)

Standard hydrogen electrode: (S.H. E.) :

Pt(s) | H2(g, 1 atm) |2H+(aq, 1M)

SHE with copper electrode notation:

Pt(s) | H2(g, 1 atm) |2H+(aq, 1M) || Cu2+(1M) | Cu(s)

Use pt electrode for the ion with two different charges:

Pt(s) | Sn2+(aq), Sn4+(aq) || Ag+(aq) | Ag(s)

7. Write cell notation for the following two half cell reactions.

Cu(s) Cu2+(aq) + 2e-

Ag(s) Ag+(aq) + e-

8. Write cell notation for the zinc electrode with hydrogen electrode.

9. Write overall reaction for the following cell notation

Sc(s)| Sc3+(aq) ||Zn2+(aq)|Zn(s)

10. Write a cell notation in which Al(s) is oxidized to Al3+ and Zn2+ is reduced to Zn(s)

11. Draw a voltaic cell in which silver ion is displaced from solution by aluminum metal. Label the cathode and anode. Show the direction of the flow of electrons. Also indicate the direction of flow of cations and anions from a KNO3 (aq) salt bridge. Write two half cell reactions and overall reaction. Identify oxidizing and reducing agent.

Overall reaction and two half cells E°red. Values are given

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12. Determine E°cell for the following reaction:Fe(s) + Cu2+(aq) Fe2+(aq) + Cu(s)

Fe2+ + 2e- Fe(s) E° = -0.44VCu2+(aq) + 2e Cu(s) E° = 0.34V

13. Calculate E°cell

Zn(s) + Cu++(aq) Zn++(aq) + Cu(s)

Zn(s) Zn++(aq) + 2e- Cu++(aq) + 2e- Cu(s)

Zn2+/Zn(s) = -0.76V; Cu2+/Cu(s) = 0.34V

Two half cells oxidation reactions are given

Cu(s) Cu2+(aq) + 2e-

Ag(s) Ag+(aq) + e-

Al(s) Al3+(aq) + 3e-

Zn(s) Zn+2(aq) + 2e-

Two half cells reduction/oxidation reactions are given

2Fe3+(aq) + 2e- 2Fe2+(aq) Zn(s) Zn2+(aq) + 2e-

Cu2+(aq) + 2e- Cu(s)H2(g) 2H+(aq) + 2e-

Two half cells reduction reactions are given

Zn+2(aq) + 2e- Zn(s) E° = -0.763Cl2(g) + 2e- 2Cl-(aq) E° = 1.360

Practice problems

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14. PbO2(s) + Pb(s) + 2H2SO4 2PbSO4(s) + 2H2O(l)

15. Ag(s) Ag1+(aq) + e- E°ox = -0.80VCu(s) Cu2+ + 2e- E°ox = -0.34V

16. Fe2+(aq) Fe3+(aq) + e- E°ox = -0.77VCo2+(aq) Co3+ + e- E°ox = -1.82V

17. Br2(l) + 2e- 2Br-(aq) E°red = +1.07VI2(s) + 2e- 2I1-(aq) E°red = +0.54V

18. Rh3+(aq) + 3e- Rh(s) ReductionCd(s) Cd2+(aq) + 2e- Oxidation

E°Rh3+/Rh = 0.80V and E°Cd2+/Cd = -0.40V 19. Ni2+(aq) + 2e- Ni(s) E°Ni2+ = -0.25V

Cr3+(aq) + 3e- Cr(s) E°Cr3+ = -0.74V

20. Ni2+(aq) + 2e- Ni(s) E°Ni2+ = -0.25VCr3+(aq) + 3e- Cr(s) E°Cr3+ = -0.74V

21. Write line notation for the following redox reaction.

5Fe(s) + 2MnO4-(aq) + 16H+(aq) 5Fe2+(aq) + 2Mn2+(aq) + 8H2O(l)

22. Calculate E°cell for the following reaction

Al(s) + NO3-(aq) + 4H+(aq) Al3+(aq) + NO(g) + 2H2O(l)

23. Calculate ∆G° for the following reaction.I2(s) + 2Br-(aq) 2I-(aq) + Br2(l)Br2 /Br-= 1.09V and I2/I- = 0.54V

24. Calculate Ecell for the following reaction (ans: 1.41V)

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3Cu(s) + 2MnO4-(aq) + 8H+(aq) 3Cu2+(aq) + 2MnO2(s) + 4H2O(l)

[MnO4-]0 = 2.0M, [H+]0 = 1.0M, [Cu2+]0 = 0.010M

25. Calculate equilibrium K for the following redox reaction.

Cu(s) + 2H+(aq) Cu2+(aq) + H2(g)

∆G = -nFE where F is a Faraday constant = 96,485 or 96,500 C/mol.e-

26.Draw a diagram, show balanced equations, and write the notation for a voltaic cell that consists of one half cell with a “Cr” bar in Cr(NO3)3 solution, another half-cell with an “Ag” bar in an AgNO3 solution, and a KNO3 salt bridge.

27.Calculate the standard free energy change at 25°C for the following reaction. The standard cell potential is 1.10V at 25°C.

Zn(s) + Cu2+(aq) Zn2+(aq) + Cu(s) Answer: -212kJ

28.Balance the following redox reaction in acidic solution.


29. Write the cell reaction for the following voltaic cell.Tl(s)| Tl+(aq) || Sn2+(aq) | Sn(s)

30. Write the cell reaction for the following voltaic cell.Zn(s)| Zn++(aq) || Fe3+(aq), Fe2+(aq)

31. Write the cell reaction for the following voltaic cell.Zn(s)| Zn++(1.0M) || H+(1.0M)|H2(1.0atm)|Pt(s)

32. Calculate E°cell for the following cell.Zn2+(aq) + 2Fe2+(aq) Zn(s) + 2Fe3+(aq) Zn2+/Zn = -0.76V

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Fe3+/Fe2+= 0.77V

33. Draw a diagram, show balanced equations, and write the notation for a voltaic cell that consists of one half cell with a “Cr” bar in Cr(NO3)3 solution, another half-cell with an “Ag” bar in an AgNO3 solution, and a KNO3 salt bridge.

34. Calculate the standard free energy change at 25°C for the

following reaction. The standard cell potential is 1.10V at 25°C.

Zn(s) + Cu2+(aq) Zn2+(aq) + Cu(s)

Answer: -212kJ



36. Write the cell reaction for the following voltaic cell.Tl(s)| Tl+(aq) || Sn2+(aq) | Sn(s)

37. Write the cell reaction for the following voltaic cell.Zn(s)| Zn++(aq) || Fe3+(aq), Fe2+(aq)

38. Write the cell reaction for the following voltaic cell.Zn(s)| Zn++(1.0M) || H+(1.0M)|H2(1.0atm)|Pt(s)

39. Calculate E°cell for the following cell.Zn2+(aq) + 2Fe2+(aq) Zn(s) + 2Fe3+(aq)

40.Write cell notation for Zn(s) + 2Fe3+(aq) Zn2+(aq) + 2Fe2+(aq)

41.Determine E°cell for the following reaction:Fe(s) + Cu2+(aq) Fe2+(aq) + Cu(s)Fe2+ + 2e- Fe(s) E° = -0.44VCu2+(aq) + 2e Cu(s) E° = 0.34V

42.Use the data below to answer the following questions:Sn4+(aq) + 2e- Sn2+(aq) E° = +0.13VSn2+(aq) + 2e- Sn(s) E° = -0.14V

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a. Which is the stronger reducing agent?b. Calculate E°cell for the above two half cell reactions.c. Calculate free energy ∆G° for the above cell.

(F = 96,487 C/e-)

43.The charge on one electron is 1.60219 x 10-19C. What is the charge of one mole of electrons?

44.Write overall reaction for the following two half cell reactions:Zn2+(aq) + 2e- Zn(s)Fe3+(aq) + e- Fe2+

45.Calculate E°cell for the following reaction;2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g)E°H2O/H2 = -0.83V; E°Na+/Na= - 2.71V

46.When copper foil is placed in a silver nitrate solution, the solution turns light blue and silver precipitates. What is the equilibrium constant for the following reaction:

Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s) Cu(s) Cu2+(aq) E° = -0.34VAg+(aq) Ag(s) E° = +0.80V

47.How many faradays of electricity are given off in this spontaneous reaction when 190.5g of copper metal are used up for the above reaction?

48.What is the cell voltage for the following cell at room temperature?Zn(s) | Zn2+(aq, 0.010M) || H+(aq, 2.5M)|H2(g, 0.30 atm)Zn2+/Zn(s) = 0.76V

49.Calculate Ecell for the following concentration cell:Cu(s) Cu2+(aq, 0.10M) + 2e-

Cu2+(aq, 1.0M) Cu(s)

50.Consider a Galvanic cell that uses the

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reaction:Zn(s)+2H+(aq) Zn2+(aq) + H2(g)Calculate Ecell at 25°C when [H+] = 1.0M, [Zn2+] = 0.0010M, and PH2 = 0.10atm.E°Zn2+Zn(s) = -0.76V (answer: 0.88V)

51.Consider a Galvanic cell that uses the reaction:Cu(s)+ 2Fe3+(aq) Cu2+(aq) + 2Fe2+(aq)What is the potential at 25°C when [Fe3+] = 1.0 x 10-4M, [Cu2+] = 0.25M, and [Fe2+]= 0.20M (answer: 0.25V)

52.The following cell has a potential of 0.55V at 25°C:Pt(s)|H2(1 atm)|H+(?M) || Cl-(1M)|Hg2Cl2(s)|Hg(l)What is the pH of the solution in the anode compartment? (answer:4.6)

53.Balance the following redox reaction in an acidic solution.Br-(aq) + Cr2O7

2-(aq) Br2(g) + Cr3+(aq)

54.How many amperes must be passed through a Downs cell to produce sodium metal at a rate of 30.0kg/h? (answer: 34,700)

55. For the reaction: Zn2+(aq) + Cu(s) <-> Zn(s) + Cu2+(aq)

Zn2+(aq) + 2e- Zn(s) E° = -0.76VCu Cu2+(aq) + 2e- E° = -0.34V

a. Calculate E°cell.b. Calculate the ∆G°.

56. For the reaction: VO2

+(aq) + 2H+(aq) + e- VO2+(aq) + H2O(l) E°= +1.00VZn2+(aq) + 2e- <-> Zn(s) E°= -0.76V

a. Calculate E°cell. b. Calculate the ∆G°.

57. Calculate Ecell for a galvanic cell based on the following half reactions at 25°C.

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Cd2+(aq) + 2e- Cd(s) E° = -0.40VPb2+(aq) + 2e- Pb(s) E°= -0.13V

Where [Cd2+] = 0.010M and [Pb2+] = 0.100M.

58.Calculate Ecell for a galvanic cell based on the following half eactions at 25°C.FeO4

2-(aq) + 8H+ +3e- Fe3+(aq) + 4H2O E° = -0.40VO2 + 4H+(aq) + 4e- 2H2O E°= -0.13V

Where [FeO42-] = 0.0020M and [Fe3+] = 0.0010M.

[O2] = 0.000010 atm pH = 5.2

59.For a galvanic cell the half reactions are:Cu2+(a) + 2e- Cu(s) E° = 0.34VCr2O7

2-(aq) + 14H+ + 6e- 2Cr3+(aq) + 7H2O E° = 1.33VCalculate equilibrium constant K for the above cell.

60.Consider the reaction: Ni2+(aq) + Sn(s) Ni(s) + Sn2+(aq) Ni2+/Ni -0.23V, Sn2+/Sn(s) -0.14Va. Calculate E°cell. b. Calculate equilibrium K at 25°C.

61.How many grams of copper can be reduced by applying a 3.00 A current for 16.2 min to a solution containing Cu2+ ions?

62.What volume of H2 gas and O2 gas is produced by electrolyzing water at a current of 4.00 A for 12.0 minutes (assuming under ideal conditions)?

63.The following cell has a potential of 0.55V at 25°C:Pt | H2(1 atm) | H+ (?M) || Cl-(1M | Hg2Cl2(s) | Hg(l)

Write overall reaction and calculate Ecell for hydrogen electrode?

64.The following cell has a potential of 0.55V at 25°C:Pt | H2(1 atm) | H+ (?M) || Cl-(1M | Hg2Cl2(s) | Hg(l)

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What is the pH of the solution in the anode compartment?

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