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This is a pretty basic question, and I know it has something to do with conductivity, but I'm not quite sure how they are related.

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  • $\begingroup$ Blake, please see my edits -- if you're unhappy with anything I changed, please feel free to change it back, or roll back my edit entirely. $\endgroup$ – hBy2Py Jan 30 '17 at 21:37
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The reasoning here is two-fold. The solubility of most electrolytes increases with temperature, and water's ionization constant also increases with temperature. On the whole this means more ions, and thereby better conductivity.

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  • $\begingroup$ Can you clarify on the ionization constant because I thought it decreased when temperature increased. $\endgroup$ – jkd Jan 31 '17 at 1:49
  • $\begingroup$ @jakekimds The value of $\mathrm{p}K_\mathrm{a}$ does decrease with increasing temperature, yes. But, this means that the proper ionization constant, $K_\mathrm{a}$, increases with increasing temperature. $\endgroup$ – hBy2Py Jan 31 '17 at 3:58
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ringo makes good points in his answer. Additionally, though, the increased temperature enhances mass transfer of ions to/from the electrode surfaces by at least two mechanisms:

  1. Higher temperature results in lower electrolyte viscosity, leading to a thinner fluid dynamic boundary layer and concomitant greater mass transfer to/from the electrode surfaces.

  2. Higher temperature also increases the diffusivities of the electrolyte solutes, which also contributes to increased mass transfer to/from the electrodes.

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  • $\begingroup$ very good additional points. $\endgroup$ – MaxW Jan 30 '17 at 21:04

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