Maharashtra BoardEnglish MediumSTD 12 ScienceChemistryElectrochemistry2 Marks
Question
Obtain a relation between cell potential and Gibbs energy for the cell reaction.
✓
Answer
Consider a galvanic cell which involves $n$ number of electrons in the overall cell reaction. Since one mole of electrons involve the electric charge equal to one Faraday (F) which is equal to 96500 C, the total charge involved in the reaction is, Electric charge $= n \times F$ If Ecell is the cell potential, then Electrical work $= n \times F \times E _{\text {cell }}$ According to thermodynamics, electric work is equal to decrease in Gibbs energy, $-\Delta G$, we can write, Electric work $=n \times F \times E_{\text {cell }}=-\Delta G$ $\therefore \Delta G=-n F E_{\text {cell }}$ Under standard conditions, we can write $\therefore \Delta G^0=-n F E_{\text {cell }}^0$ where $E_{\text {cell }}^0$ is the standard cell potential and $\Delta G^0$ is the standard Gibbs free energy change.
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