Neutralising peroxide / H2SO4 / Cobalt extract solution with NaOH.

This is part of the Li-Ion battery recycling process which will eventually be turned into a full video later on, but for now, enjoy watching some oxygen degassing from the residual peroxide in solution. The lovely red solution of Co2+ ions soon turns to a sludgy green-brown Cobalt hydroxide precipitate. Normally it would be a beautiful blue, but with all this peroxide in solution, it's rapidly oxidised to Co(OH)3, or more likely, Co2O3.
Classic glowing splint trick, proving it's O2.