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I'm thinking in the following experiment:

A) Two (non mixable (like water and oil)) liquids are going to lie in a container, in the extremes of the container there are two electrodes, those electrodes will have a potential difference $\Phi$. Just as the figure $1.a)$.

I'm looking for some interesting liquids that mix, change of color when a voltage difference is present.

enter image description here

B) The next one is really similar, now there are some solid particle present, analogously I look for a mixture that has different properties when a voltage difference is present.

I'm a physics student that want to study different properties of mixtures when applying different voltage differences, and maybe study the diffusion of the solid particles when they mix, if the diffusion coefficient is grater, etc.

Any help with the liquids that has this property is really appreciated.

Cross posted Physics stack Exchange

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  • $\begingroup$ I was just looking up some ancient papers on electrophoresis (1950s) before they had gels or even paper electrophoresis. They had to watch the fluid with special optics to catch when the refractive index changed as the material moved through the apparatus. When I'm back in lab I'll try to post the links, might be interesting for you. $\endgroup$ – user137 Nov 13 '14 at 7:38
  • $\begingroup$ Here is a paper about KCl diffusion in water using a device to image the change in refractive index. This paper discusses electrophoresis of proteins in solution. $\endgroup$ – user137 Nov 13 '14 at 18:19
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I won't comment on B for the moment, but liquid-liquid interface electrochemistry is quite a vibrant field. There's a review of it here, if you're interested. The simplest interaction involves ions: if one applies a potential across the interface of sufficient strength and polarity, the energy barrier of transferring a given ion from one phase to the other can be overcome. If you do this with something like a solvatochromic dye, it will change colour as it moves from one phase to the other. (It would have to be something that doesn't partition into the second phase easily on its own, of course) One could also have some reagent in one phase that reacts with the ion being pushed across the interface that produces some coloured product. (iodide-starch, perhaps?) There are also voltage-sensitive dyes, though I don't have any experience with them.

One thing to note is that neither water nor oils and other immiscible solvents are generally very conductive. To keep the cell resistance down to a reasonable level, it will be necessary to dissolve electrolytes in both. Things like Tetrabutylammonium hexafluorophosphate are commonly used as electrolyte in non-aqueous electrochemistry.

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