Advanced Topic 566 of 1102 Acids, Bases & Electrochemistry
Cell Potential and Free Energy
Delta G equals minus n F E, linking voltage to Gibbs energy.
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In-depth explanation of Cell Potential and Free Energy
The change in Gibbs free energy for a cell reaction is related to its cell potential by delta G = -nFE, where n is the number of moles of electrons transferred per mole of reaction and F is the Faraday constant of 96485 C per mole. This relationship links an electrical measurement to the thermodynamic driving force of a reaction. It gives the maximum electrical work a galvanic cell can deliver under reversible conditions. A positive cell potential corresponds to a negative free energy change, meaning the reaction is spontaneous. The relationship also allows standard free energies to be derived from tabulated potentials.
Going deeper: Cell Potential and Free Energy
Key ideas: delta G standard = -nF E standard, with F = 96485 C/mol, so the result is in J/mol; divide by 1000 for kJ. For the Daniell cell, n = 2: delta G = -2 x 96485 x 1.10 = -212 kJ/mol. Maximum electrical work equals -delta G. Under any conditions delta G = -nFE.
Common mistakes and connections: Errors: forgetting to convert J to kJ, using the wrong n for the balanced equation as written, and scaling E when coefficients double (delta G doubles, E does not). The sign relation links E positive with delta G negative. Combines with delta G standard = -RT ln K.
Visualization of Cell Potential and Free Energy
Delta G = -nFE: a larger positive cell potential means a more negative free energy change; the Zn-Cu cell at 1.10 V gives -212 kJ per mole. The interactive lesson shows this as a live animation or chart.
Worked example and use case
For a zinc-copper cell with E = 1.10 V and n = 2, delta G = -2 × 96485 × 1.10 = -212 kJ per mole of reaction.
Frequently asked questions about Cell Potential and Free Energy
What is Cell Potential and Free Energy?
Delta G equals minus n F E, linking voltage to Gibbs energy.
Is Cell Potential and Free Energy a beginner, intermediate or advanced topic?
Cell Potential and Free Energy is a advanced topic in Acids, Bases & Electrochemistry. It builds on beginner and intermediate topics, so review those first if needed.
What should I learn before Cell Potential and Free Energy?
Study these earlier topics in Acids, Bases & Electrochemistry first: Electrochemical Series, Spontaneity from Cell Potential, Nernst Equation.
What comes after Cell Potential and Free Energy?
The next topics in Acids, Bases & Electrochemistry are Cell Potential and Equilibrium and Concentration Cells.
Can I practise Cell Potential and Free Energy with quizzes?
Yes. The interactive lesson includes a self-check question on Cell Potential and Free Energy, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Where Cell Potential and Free Energy fits in Acids, Bases & Electrochemistry
Cell Potential and Free Energy is topic 56 of 105 in Acids, Bases & Electrochemistry.