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CAIE A-Level Chemistry 24.2.9 Nernst equation

Practise applying the Nernst equation to calculate electrode potentials from concentrations, pH and half-cell data.

Syllabus
2028–2030
Course
Chemistry 9701
Level
A2

Exam points

  • substitute E°, z and concentration terms into E = E° + (0.059/z) log([ox]/[red])
  • calculate electrode potentials for Cu2+/Cu, Fe3+/Fe2+ or metal-ion half-cells
  • convert given mass, pH or concentration data before using the Nernst equation

24.2.9—Nernst equation question 1

[Maximum number: 2]

Some electrode potentials are shown in Table 3.1.

Table 3.1

Table 3.1

Another electrochemical cell is set up using an Fe3+/Fe2+\mathrm{Fe}^{3+} / \mathrm{Fe}^{2+} electrode and an alkaline ClO−/Cl−\mathrm{ClO}^{-} / \mathrm{Cl}^{-} electrode.

The concentration of Fe3+\mathrm{Fe}^{3+} is 1000 times greater than the concentration of Fe2+\mathrm{Fe}^{2+} in the Fe3+/Fe2+\mathrm{Fe}^{3+} / \mathrm{Fe}^{2+} electrode. All other conditions are standard.

Use the Nernst equation to calculate the E value of the Fe3+/Fe2+\mathrm{Fe}^{3+} / \mathrm{Fe}^{2+} electrode.

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