Sciencemadness Discussion Board

Diffusion??

Saerynide - 9-2-2004 at 10:14

This has been bugging me for a while.

I have an anolyte of pure water and a catholyte of saturated salts bridged by a paper towel strip (both solutions are of equal volume). After turning on the power and giving it some time for the anions to flow across the bridge, the volume of anolyte increases and the volume of the catholyte decreases.

I cant figure out why. I ruled out capillary attraction because both solutions started with equal volumes. If they flow into each other, one wouldnt flow into the other faster, would it?

I also didnt think it would be osmosis, cause then the anolyte (pure water) should be diffusing to the catholyte, not the other way around, right?

hodges - 9-2-2004 at 15:34

If the ion concentration is different in the two solutions, there will be a net flow - likely from the stronger to the weaker solution.


Try leaving your two solutions sit without any power flowing and see if the same things happens. That would rule out electrolytic action if so.