sulfuric acid went black like it burned it

[Flattop]

Ok guys not sure where I went wrong . Was evaporating sulfuric acidon low heat and it looks likeit is burned. Not sure ifthis is right or where it went wrong any ideas thank you

 

[jeneje]

Why are you evaporating H2SO4, Are you doing a gold cell?
Ken

 

[Geo]

sounds like organic contamination. was it stored in a plastic container or did you place it in one after evaporating?

 

[Flattop]

Ken,I was concentrating it to use Lazersteve subzero method for nitric recipe. Geo, yes it was it was stored in a plastic bag a battery electrolyte that I bought from Napa autozone. I let it sit overnight to see if anything would settle out, and it formed a film on top

 

[Geo]

what were you evaporating it in. was it glass? theres alot of information you left out.

 

[Flattop]

I use a propane hot plate with a metal baking dish on top of that with sand on top of the baking plate then I place a Pyrex glass beaker on top of that and for the sulfuric acid into the glass beaker I put it to load heat and slowly start warming it up and slowly increased temperature until I seen the water fume starting to evaporate I then slowly increased temperature and let it sit for 2 1/2 hours it then started to discolor so I turned it off by the time it cooled off it was black

 

[Geo]

that is not auto battery electrolyte. if you are sure about where you purchased it, you can let them know that their stock is contaminated. ive had it turn dark, like dark blonde or honey but never black.

 

[butcher]

I believe something has contaminated the battery acid, did you stir with some metal tool, or did the acid at anytime come into contact with metal, was the glass ware clean to begin with? I suppose there might be a slight trace of iron in the acid from manufacturing, but it seems odd there would be enough to color the acid black upon concentration, battery acid is normally very pure, so as not to contaminate the battery, you will not burn the acid easily as long as it remains a liquid, although if there were contaminates you could possibly precipitate them out and burn them like organics or metal salts.

 

[Flattop]

No butcher I did not stir it with any thing at all and took it right from the plastic bag container I got from Napa auto right to the glass dish witch was also new I rinsed it out with hot water and used a paper towel to dry it but it was clean so I don't know. Guess the big question is what to do with it now and thank you all for your help

 

[Flattop]

Does anyone think it could be used as is for something or would it be best to neutralize and dispose of it