E cell voltage

[ThiaminePyroPhosphate]

Hi ,

I have a question regarding the cell voltage of a galvanic cell under non-standard conditions. From the equation E=E - (RT/nF)lnQ, it seems that the only way to change the voltage is by adjusting the concentration of ions in anode/cathode beaker. My question is, does the amount/mass of either the anode or electrode cathode affect the voltage of the cell even though they're not included in the equation? I would assume yes, because for example, the mass of the anode electrode may serve as a limiting reagent?

Lastly, does this equation E=E - (RT/nF)lnQ, apply only to galvanic cells or electrolytic cells as well?

Thanks!

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[Teleologist]

The physical properties of the anode and cathode can certainly affect the kinetics of the system. Thermodynamically, I'm pretty sure the answer is no in most scenarios, and voltage is a thermodynamic property.

 

[The Brown Knight]

For your second question, Nernst equation is generally used to calculate the the voltage an electrochemical reaction would provide in a galvanic cell. But you can still use it to calculate the external voltage needed to drive an electrolytic reaction. In biochemistry, if you know concentrations of an ion outside and inside a membrane you can use the Nernst equation to calculate the electrochemical gradient of that ion across the membrane (something like a galvanic cell) or the energy needed to push the ion against that gradient (something like an electrolytic cell)

 

[justadream]

@ThiaminePyroPhosphate

My understanding is that the voltage can only be altered if you
1) Alter concentrations
2) Alter the components altogether (e.g., replace one of the anode/cathode)

The mass of the anode/cathode would affect the total amount of current you could produce (more mass means you can run the cell longer).