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Since pH is a measure of the effective concentration of $\mathrm{H}^+$ ions a solution, I expect that an electric field applied to a solution will create a pH gradient. The higher concentration of $\mathrm{H}^+$ ions (corresponding to lower pH) should be close to the anion, and a lower concentration of $\mathrm{H}^+$ ions (corresponding to higher pH) should be closer to the cation.

This is a simple yes or no question. Does an electric field create a pH gradient as I described above? (If not, can you please provide an explanation?)

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I would say that it makes sense that yes, it will create a pH gradient. I don't know about the order of magnitude of such a gradient and how it depends on the voltage. Let's hope someone does the experiment :) – cinico Dec 16 '13 at 13:47
Let's also hope someone provides a more thorough physical analysis... :) – becko Dec 16 '13 at 13:54
Basically, we can take electrolysis as an example. You surely can promote a gradient of H+ concentration. I just don't know how much is it in terms of pH. – cinico Dec 16 '13 at 17:41

1 Answer 1

up vote 4 down vote accepted

Yes, applying an electric field does create a pH gradient and in fact you can observe this simply by adding a suitable indicator to your system. For example see the section Demonstration of pH Gradient Formation in this article.

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