[Jose Luis Mg]

I took out a reaction between sodium hypochlorite (Ac) manganese dioxide and coal. Manganese dioxide and coal comes from a battery.
The reaction releases a gas, smell nice at first, but becomes very pervasive within about 20 seconds. The gas is white and cause eye irritation. It causes nausea and headache.
The reaction produces sodium permanganate and gas.

NaClO + MnO2 + C ---> NaMnO4 + gas

Would like you to help me know what is that gas

Thank you.

[Borek]

It is not a simple gas. If it is white, it is most likely a mist - caustic and probably mixed with chlorine.

[KaliyaK]

Hi, i redid your experiment using regular unscented 5% bleach and washed manganese dioxide carbon mix from Zn/C batteries. I got no reaction.
Manganese dioxide only reacts with hypochlorite to form permanganate in strong hypochlorite solution with sodium hydroxide.
What source of sodium hypochlorite did you used? What was the condition of your MnO2/C mix? Was it free of water soluble compounds?
The gas should have came from side reactions of contaminants present in the reagents.

[Jose Luis Mg]

I use sodium hypochlorite from a bleach called "Cloralex". It don't say the hypochlorite concentration.
I realized that sodium permanganate is formed without sodium hydroxide and i don't know why.
yes, well i think, i just opened the battery and extracted the mix, its a black powder and catalyzes the descomposition on H2O2. i don't know if it's free of water soluble compounds, i was thinking that probably could be phosgene the produced gas, it smell fine in low concentration.

[billnotgatez]

it smell fine in low concentration.

Oh My Goodness
Sniffing unknown reactions is not the best thing to do