[Miles111]

Hello, I've recently started several projects involving electrolysis. I notice the water in the bottle which I'm using to contain said water has started to turn yellow. Is this fliud dangerous? My electrodes are two stainless steel spons with the scoop cut off.

[shelanachium]

Are your solutions acidic? If so this could be Fe3+ from oxidation of the iron in the stainless steel, which although inert to air and many other reagents will not resist electrolytic oxidation. Fe3+ solutions are harmless.

However stainless steel also contains chromium and especially if the solutions are alkaline this may be producing yellow chromate, which is toxic. Chromate is easily tested for; for example acidify, add hydrogen peroxide and ether and shake. If chromate is present the ether will turn blue.

[Miles111]

I'm not using any electrolyte; just plain tap water. I also tried it with copper wire as the electrodes, which made the liquid blue.

[shelanachium]

Even tap water contains some electrolyes though it will not conduct very well. If your tapwater is soft it is likely to be slightly acidic, and if hard slightly alkaline.

The hydrated copper (II) ion Cu2+ is blue and this accounts for the colour obtained using a copper electrode. If ammonia is added to such a solution the blue colour deepens and intensifies. As I said the yellow colour with stainless steel could be either Fe3+ or [CrO4]2- and these are easily distinguished.

[enahs]

It is from Iron as shelanachium said, but it is from the spoon. It s producing what is known a Iron(III) hydroxide, sometimes called oxide-hydroxide, or Yellow Iron Oxide.

You just discovered the trick that water filters like Brita and others use to use to sale their product on commercials and such.


They would specifically use a iron electrode to produce the Yellow color. They would then use the same electrodes on the purified water, and no Yellow color would produce. This is because the filters removed enough ions to make the water no longer conduct, not allowing the iron to oxidize.
But if you then put just a tiny pinch of salt in the water, it would again produce the Yellow color (they did not show you this part though when trying to sale you the filters!).

[mhoy]

Well, I think it could be get change the water change during that kind of filtering. But some says it could be happen when your water is too dirty. But if the water is clean they look crystal and smooth.