Sciencemadness Discussion Board

Electrolysis usin FeS2

guy - 8-5-2004 at 16:38

I used FeS2 as the anodes and cathodes for electrolysis of water with some NaHCO3. A gas formed and it stunK. I don't know if it was H2S or SO2.

JustMe - 8-5-2004 at 16:56

I am way out of date on electrochemistry, so I don't know either, except for this:

H2S: rotten egg smell

SO2: not so much a smell as pungent.

Stunk (?) not precisely descriptive enough, pick one from column A or B (or both?).;)

[Edited on 9-5-2004 by JustMe]

guy - 8-5-2004 at 17:06

I have never smelled a rotton egg before so I don't know what rotten eggs smell like. The smell wasn't really strong like chlorine, so maybe it was SO2

BromicAcid - 8-5-2004 at 17:16

Did your solution change color? How about your electrodes, was there apparent errosion? These might be able to tell you if the electrodes participated to a significant degree in the reactions taking place. It is my guess that either or both gasses may have formed, the reaction of nascant hydrogen on the electrodes may have reduced the sulfur to the hydrogen sulfide or it may have just reduced in the electrode reduction. Also oxidation does occur at the anode so SO2 could be produced. Personally I think H2S was produced just with the way you describe the smell as stinking, SO2 is more of a feeling then a smell to me.

guy - 8-5-2004 at 17:33

I don't think my soluton changed colors. After I smelled the gas, I stopped doing it, so there wasn't really any sign of erosion.

guy - 8-5-2004 at 19:18

I tried the experiment again and I'm pretty sure it was H2S.

The gas came out of the Positive end.

______

Also I tried the experiment in a brine solution.

H2 and Cl2 evolved. The Pyrites eroded and there was rust spots. The soloution also had an insoluble yellow-orange substance, maybe Fe(OH).

Proteios - 9-5-2004 at 09:57

Quote:
Originally posted by guy
I used FeS2 as the anodes and cathodes for electrolysis of water with some NaHCO3. A gas formed and it stunK. I don't know if it was H2S or SO2.



What a very bizarre thing to do! Why?

Very hard to see how you could get SO2.... you get H2S from electrolyisis of S2-/HS- at the anode.



O yeah... btw... H2S is extrememly toxic. Comparable with cyanide, although is exteremely potent smell ususallly stops too many fatalities (however beware....the human body does habitualise (after a while you cant smell it) to H2S). Plus your electrolysis is unlikely to produce much gas. Handle the solution with care afterwards. The concentration of S2- and HS- in the solution will be comparitavely very high compared to that of the gas you can smell.


[Edited on 9-5-2004 by Proteios]

[Edited on 9-5-2004 by Proteios]

guy - 9-5-2004 at 16:07

I think the Sodium bicarbonate in the solution reacted with the dissolved H2S to for Na2S.