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I recently got hold of an old blowlamp that had not been touched for more than 30 years. The fuel tank of the blowlamp is made of brass. I poured the old kerosene from the blowlamp into a clean polyethene flask, the kerosene was clear and quite green in color. The flask got about half full.

The next day the kerosene had turned colorless and there was a brown precipitate. The flask was not shaken or subjected to strong light.

What happened here? Something that had been stable for years suddenly reacting. If it is a reaction with oxygen, does oxygen diffuse that easily through kerosene?

Was the green substance an inorganic copper salt dissolved in the kerosene or was it some kind of organic "copper kerosenate"?

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  • $\begingroup$ You probably aerated the kerosene pretty well when you poured it from one container to another. The actual oxidization reaction may have taken a while, which is why you didn't observe any color change immediately. $\endgroup$ – Ilmari Karonen Dec 20 '15 at 1:00
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The brass is a metal mixture of cooper and zinc. Copper compounds are known to form blue and green salts.

Examples: Copper Chloride

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I believe that green color it's a copper compound and the copper reacted with oxygen (air) and the preciptate is copper oxide.

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Also, the oxygen solubility in hidrocarbons it's around 60/70 ppm¹. ¹Corrosion for everybody - Alec Groissman

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