HardChemistryHigh School (11–12)Electrochemistry › Galvanic Cells, Electrode Potential and the Nernst EquationNumerical

Two half-reactions are known. Cr³⁺ + e⁻ → Cr²⁺ has E° = -0.41 V…

Try it on paper first. A hint, the key idea and the worked solution are here when you need them.

Two half-reactions are known. $\text{Cr}^{3+} + e^- \rightarrow \text{Cr}^{2+}$ has $E^\circ = -0.41\ \text{V}$ . $\text{Cr}^{2+} + 2e^- \rightarrow \text{Cr}$ has $E^\circ = -0.91\ \text{V}$ . Find the Gibbs energy change for $\text{Cr}^{3+} + 3e^- \rightarrow \text{Cr}$ and the standard potential of $\text{Cr}^{3+}/\text{Cr}$ .

Need a reminder? The key ideaShow

$\Delta G^\circ = -nFE^\circ$ , with $F = 96500\ \text{C/mol}$ , and $E^\circ = \dfrac{0.0591\ \text{V}}{n}\log K$ at $298\ \text{K}$ . A reaction with $E^\circ > 0$ has $\Delta G^\circ < 0$ and $K > 1$ . When half-reactions with different numbers of electrons are added, add the Gibbs energies, not the potentials.

The worked solution

Have you tried it?

Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.

← All Problems

← Cadmium metal is placed in a solution of iron(II) ions, with E°(Cd²⁺/Cd) = -0.40 V and E°(Fe²⁺/Fe)…Excess zinc dust is stirred into 0.050 mol/L copper(II) sulphate until the reaction Zn(s) +… →

More onElectrochemistry › Galvanic Cells, Electrode Potential and the Nernst Equation

Discussion (0)

Loading…

Two half-reactions are known. Cr³⁺ + e⁻ → Cr²⁺ has E° = -0.41 V…

The worked solution

Discussion (0)

Want to go further in Electrochemistry › Galvanic Cells, Electrode Potential and the Nernst Equation?