Sciencemadness Discussion Board

Chromium Salt from electrolysis?

Magius - 28-10-2004 at 16:52

So...

Today I set up a simple electrolysis experiment. I stuck 2 NiChrome wires into dilute H2SO4 and left it running at 50V*10Amps. The solution was in a plastic container with holes drilled in the side for the anode and cathode, sealed by hot glue. I come back 3 hours later to find that the electrolysis has stopped becuase the anode snapped off(erroded?) at its entrance point, and the whole solution is a nice yellow shade. I know chromium forms a yellow colored Ion in solutions(IIRC Chrome 3+), but I thought that NiChrome was an inert electrode.

Also, the anode appeared to be undamaged, while the area where the cathode gave of the most hydrogen had turned a whitish shade, not the original color at all. It appears that this is where the choromium was stripped off, but I thought that the annode would go into solution if anything.

Whats going on?

BromicAcid - 28-10-2004 at 18:20

How thick were your electrodes? At that kind of voltage and with those amps and with such a good electrolyte the power didn't have much time to follow the metal further into solution, oxidation of your anode took place almost at the surface interface from the sound of it and continued till it ate its way though your anode and fell into another piece.

I really wouldn't have done this in a plastic container. I use a similar method to solvate nickel metal and it gets very hot. The whitish shade could be imbedded sulfate that precipitated from the cooled solution. Or oxidized and re-reduced metal salts.

neutrino - 29-10-2004 at 15:47

It sounds to me like he used a thin heating wire.

Be careful sround that solution. Nickel salts are very toxic.

Wattage

MadHatter - 30-10-2004 at 09:08

You came back after 3 hours ? It may have happened in minutes considering you're using
wire and pushing 500 watts !