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This is for the case of a hydrogen fuel cell. My reasoning was that, similar to rates of reactions, increasing gas pressure increases the 'concentration' of the molecules, thus there's more reactions. I guess that that would more likely affect the current though.

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  • $\begingroup$ When working with galvanic cells always start by writing the redox reactions as they occur. This will help answer your question. $\endgroup$ Feb 22, 2023 at 13:00
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    $\begingroup$ Theoretically, as in the answer below, there's little effect. Practically, though, pressure on a physical cell can force the electrodes into closer proximity, reducing cell resistance and increasing current. This can show as increased voltage, if the meter or circuit has finite resistance. Of course, sufficient pressure could destroy the cell, too. $\endgroup$ Feb 22, 2023 at 17:30

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Pressure has significant influence on the cell voltage only if some active components of redox systems are gaseous.

Otherwise, the effect is very small, depending on slight volume and/or compressibility changes. These can be both ways and higher pressure would support the state with smaller volume, with (near) negligible effect.

There cannot be therefore said in general if higher pressure would increase or decrease the cell voltage.


In later added context of hydrogen fuel cells, the cell voltage would increase with pressure of hydrogen and oxygen gases for two reason:

  • Thermodynamically, electrode potential of the oxygen electrode would increase due increased activity of oxidant(oxygen). And vice versa for hydrogen as reductant. Both effects would increase the open voltage of the hydrogen fuel cell.
  • Kinetically, increased pressures would increase rates of redox reactions, decreasing the cell voltage drop under the load, so it would for the given load provide the dynamic part of voltage increase.

There will be also possible minor effects caused by pressure affecting geometry of the cell design.

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  • $\begingroup$ Sorry, I realised now that I never gave context. I just editted the question; I was referring to the hydrogen fuel cell. $\endgroup$
    – cabbagesss
    Apr 1, 2023 at 12:40
  • $\begingroup$ I have updated the answer. // Always include enough relevant details of the question purpose, context or background to make the question clear, preventing misunderstanding and need of clarification. $\endgroup$
    – Poutnik
    Apr 1, 2023 at 13:11

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