Worksheet: The Nernst Equation

In this worksheet, we will practice using the Nernst equation to calculate reduction potentials under nonstandard concentrations.

Q1:

A battery is dead when it has no cell potential. Consider a battery with the following overall reaction. Cu()+2Ag()2Ag()+Cu()saqsaq+2+ The standard electrode potentials for the half-cells in this battery are given in the table.

Half-EquationCu()+2eCu()2+aqsAg()+eAg()+aqs
Standard Electrode Potential, 𝐸()V+0.340+0.7996

To 2 significant figures, what is the value of 𝑄 when this battery is dead at 298.15 K?

  • A6.8×10
  • B3.4×10
  • C5.9×10
  • D4.0×10
  • E3.4×10

If a particular dead battery is found to have [Cu]2+ = 0.11 M, what is the concentration of silver ions?

  • A5.6×10 M
  • B3.8×10 M
  • C0.11 M
  • D3.2×10 M
  • E0.22 M

Q2:

Calculate to 2 significant figures the equilibrium constant at 25C for the following reaction.

HO()H()+OH()2+laqaq

Note that each standard electrode potential is expressed per mole of the half-reaction shown in the table.

Half-Equation2H()+2eH()+2aqg2HO()+2eH()+2OH()22lgaq
Standard Electrode Potential, 𝐸()V0.0000.8277
  • A1.0×10
  • B1.0×10
  • C1.0×10
  • D1.0×10
  • E1.0×10

Q3:

Using the standard electrode potentials shown in the table, calculate to 2 significant figures the equilibrium constant at 373 K for the following reaction.

Hg()+4Br()[HgBr]()2+42aqaqaq

Half-EquationHg()+2eHg()2+aql[HgBr]()+2eHg()+4Br()42aqlaq
Standard Electrode Potential, 𝐸 (V)+0.851+0.21
  • A7.4×10
  • B6.8×10
  • C2.1×10
  • D1.6×10
  • E4.5×10

Q4:

Using the standard electrode potentials shown in the table, calculate to 2 significant figures the equilibrium constant at 373 K for the following reaction.

CdS()Cd()+S()saqaq2+2

Half-EquationCd()+2eCd()2+aqsCdS()+2eCd()+S()ssaq2
Standard Electrode Potential, 𝐸 (V)0.40301.17
  • A5.8×10
  • B1.4×10
  • C2.8×10
  • D3.1×10
  • E5.2×10

Q5:

Using the standard electrode potentials shown in the table, calculate to 2 significant figures the equilibrium constant at 298.15 K for the following reaction.

AgCl()Ag()+Cl()saqaq+

Half-EquationAg()+eAg()+aqsAgCl()+eAg()+Cl()ssaq
Standard Electrode Potential, 𝐸 (V)+0.7996+0.22233
  • A3.8×10
  • B3.6×10
  • C8.8×10
  • D1.7×10
  • E1.6×10

Q6:

In the half-cells of an electrochemical cell, 1.00 M aqueous bromide ions are oxidized to 0.110 M bromine and 0.0230 M aluminum ions are reduced to aluminum metal. Using the standard electrode potentials shown in the table, calculate to 3 decimal places the cell potential for the cell at 298.15 K. Note that standard electrode potentials are measured using 1.00 M solutions of the reacting ions.

Half-EquationBr()+2e2Br()2aqaqAl()+3eAl()3+aqs
Standard Electrode Potential, 𝐸 (V)+1.08731.662

Q7:

The half-cells of a galvanic cell consist of an aluminum electrode in a 0.0150 M aluminum nitrate solution and a nickel electrode in a 0.250 M nickel(II) nitrate solution. Using the standard electrode potentials shown in the table, calculate to 2 decimal places the cell potential for the galvanic cell at 298.15 K. Note that standard electrode potentials are measured using 1.00 M solutions of the reacting ions.

Half-EquationAl()+3eAl()3+aqsNi()+2eNi()2+aqs
Standard Electrode Potential, 𝐸()V1.6620.257

Q8:

Using the standard electrode potentials shown in the table, calculate to 2 decimal places the cell potential at 298.15 K for the cell with the following overall reaction.

Hg()+S(,0.0010M)+2Ag(,0.0025M)2Ag()+HgS()laqaqss2+

Half-EquationHgS()+2eHg()+S()slaq2Ag()+eAg()+aqs
Standard Electrode Potential, 𝐸()V0.70+0.7996

Q9:

Using the standard electrode potential data in the table, calculate the standard cell potential for the following reaction at 298 K.

Co()+Fe(,1.94M)Co(,0.150M)+Fe()saqaqs2+2+

Half-EquationCo()+2eCo()2+aqsFe()+2eFe()2+aqs
Standard Electrode Potential, 𝐸()V0.280.447

Q10:

Calculate to 3 significant figures the cell potential for the following reaction at 298 K.

Al()|Al(,0.150M)Cu(,0.0250M)|Cu()saqaqs3+2+

Half-EquationAl()+3eAl()3+aqsCu()+2eCu()2+aqs
Standard Electrode Potential, 𝐸()V1.662+0.340

Q11:

A natural spring containing manganese is found to be highly acidic. Using the diagram shown, what form of iron would you predict to be most abundant?

  • AFe(OH)()2s
  • BFe(OH)()3s
  • CFe()3+aq
  • DFe()2+aq
  • EFe()s

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