What does one ampere tell you about ideal fuel consumption?
With F = 96,485.33212… C/mol and 100% Faradaic accounting, a current I consumes H₂ at I/(2F) mol/s and O₂ at I/(4F) mol/s, while producing water at I/(2F) mol/s.
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EXPLORE THE MODEL
Fuel-cell reaction and flow account
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What this representation means
H₂/O₂ PEM reaction; 100% Faradaic accounting. 1.229 V is the standard reversible liquid-water value at 25 °C. Assumed voltage loss is not a measured polarization curve. Consumed flow differs from supplied flow.
- Remaining reactants
- 2 H₂ + 1 O₂
- Water formed
- 2 H₂O
- Conserved inventory
- 8 hydrogen atoms + 4 oxygen atoms
- Paths
- Protons through membrane; electrons through external circuit
2H₂ + O₂ → 2H₂O; ṅ(H₂) = I/(2F); P = IV
The pictured inventory and the flow calculation answer different questions. Protons cross the membrane, electrons travel through the external circuit, and oxygen is reduced at the cathode. The assumed loss changes power; it does not change the stoichiometric reactant flow at fixed current. At zero loss the power is a reversible bound, not attainable finite-rate operation.
What this model can establish
H₂/O₂ PEM reaction; 100% Faradaic accounting. 1.229 V is the standard reversible liquid-water value at 25 °C. Assumed voltage loss is not a measured polarization curve. Consumed flow differs from supplied flow.
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MAKE THE CONNECTION
If current doubles under these assumptions, what happens to calculated hydrogen consumption?
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HISTORY THROUGH EVIDENCE
A gas battery in the archive
Historical apparatus linked a gas-consuming reaction to a sustained current.
Explore how the evidence changed the explanation →