The oxidation of hydrogen by oxygen is one of the most-used reactions in fuel-cell technology.The overall reaction, which is given below, has a $\Delta$ G° value of -474 kJ/mol.What is the standard cell potential for this fuel cell?
2 H₂ (g) + O₂ (g) $\rightarrow$ 2 H₂ O(l)

Question

The oxidation of hydrogen by oxygen is one of the most-used reactions in fuel-cell technology.The overall reaction, which is given below, has a

\Delta

G° value of -474 kJ/mol.What is the standard cell potential for this fuel cell?
2 H₂ (g) + O₂ (g)

\rightarrow

2 H₂ O(l)

Quizplus · Accepted Answer

The standard cell potential ($E^\circ_{\text{cell}}$) can be calculated using the formula $E^\circ_{\text{cell}} = -\Delta G^\circ / (nF)$, where $\Delta G^\circ$ is the change in Gibbs free energy, $n$ is the number of moles of electrons transferred in the reaction, and $F$ is Faraday's constant (96485 C/mol). For the reaction given, $\Delta G^\circ = -474$ kJ/mol = $-474,000$ J/mol (since 1 kJ = 1000 J), and $n = 2$ (2 moles of electrons are transferred per mole of $O_2$ reduced). Therefore, $E^\circ_{\text{cell}} = -(-474,000 J/mol) / (2 \times 96485 C/mol) = 1.23 V$.

The Oxidation of Hydrogen by Oxygen Is One of the Most-Used