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The potential difference across a voltaic cell varies with temperature. But my question is whether the voltage increases or decreases as temperature rises. According to the Nernst equation, the two are inversely proportional, however if one were to use Gibb's Free Energy equation, as temperature increases, so does the potential difference across the cell. It would make sense that as temperature increases, there would be an increase in kinetic energy, which would probably add to the resistance and therefore make the voltage increase as well (assuming current stays the same) Do you think the potential difference would increase or decrease with an increase in temperature?

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  • $\begingroup$ Do you mean a chemical battery? $\endgroup$ – boyfarrell Apr 17 '14 at 14:00
  • $\begingroup$ @boyfarrell I think he's referring to a voltaic cell with 2 metallic half-cells. $\endgroup$ – Just_a_fool Apr 18 '14 at 7:48
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My quick read of a few articles on Q, the reaction quotient, suggest that it's generally rather small. Thus $ln(Q)$ is negative, so $ - T * ln(Q) $ is positive and the potential difference increases with temperature.

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The voltage of a Galvanic cell can both increases with temperature or decreases with temperature. You can prove using thermodynamics or using your intuition that: for Galvanic cells that get hot when working, the voltage decreases as the temperature increases; for Galvanic cells that get cold when working, the voltage increases as the temperature increases. In practice, most of Galvanic cells get hot when working but I do remember that some books mention those that get cold when working.

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