A green-colored substance formed during electrolysis, wherein the electrolyte was magnesium sulfate and minerals in tap water.

I did not have any leads to stick into the water, so I just put a 9 volt Duracel battery in the solution. The battery didn't leak.

White flakes formed after 1 minute before green substance at 10 minutes. So, what is the green stuff and what are the white flakes?

  • $\begingroup$ Longmire, was the edit from 'leads' to $\ce{Pb}$ in the 2nd paragraph correct? $\endgroup$ – hBy2Py Aug 26 '15 at 13:28
  • $\begingroup$ Brian, I had no Pb leads so I just put the battery in the solution. You definitely got the right formula for the green salt as I later checked and confirmed your statement. Thanks! $\endgroup$ – Longmire Longsnapper Aug 27 '15 at 0:49

The green material is probably an iron(II) salt, corroded from what I assume is the steel composing the positive pole of the battery. If it has a gelatinous appearance, and slowly turned orange-ish over time, my guess would be it's $\ce{Fe(OH)2}$, with any orange color deriving from slow oxidation to various iron(III) species such as the oxide-hydroxides.

Per the above link, the white flakes are possibly that same iron(II) hydroxide, prior to reaction with $\ce{O2}$ to form the green color. Alternatively, it could be $\ce{Mg(OH)2}$, or a related magnesium compound, formed at the cathode (negative terminal) from the hydroxide ion produced by reductive water electrolysis:

$$ 2\ce{H2O} + 2e^- \longrightarrow \ce{H2} + 2\ce{OH-} $$

A photograph would be tremendously helpful in facilitating identification.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.