LUEshi is my god
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Accidental reaction... what have I made?
Yesterday morning, roughly 200mL of methanol was accidentally spilled into 200mL of a saturated solution of ZnCl2 in HCl. The mixtured was observed to
go through a very exothermic reaction, making the outside of the glass jar almost too hot to touch. My first thought was that the reaction had
produced methyl chloride; however, the sinus-clearing scent of that compound was not present, and if methyl chloride had been produced, it would have
boiled off rapidly from the heat of the reaction, lowering the volume of the solution. An attempt was made to boil off the material, in hoped that at
least some of the ZnCl2 had not reacted and would be recoverable. It was found that the mystery liquid boils somewhere above 100C, as my crappy $2
Wal-Mart candy thermometer, having been in use as a stirring rod/thermometer for the past 2 months, finally broke, unfortunately before the liquid
reached its BP. Upon boiling down the stuff, I am left with a thick, black liquid, which is similar in consistency to 93% drain cleaner sulfuric acid.
As I am of a curious nature, I though I'd post what happened and see if anyone might speculate as to what reaction(s) has occured.
Edit1: After boiling the black liquid down further, it has solidified into a brown mass. It is soluble in water, and under the assumption that it
probably contains my Zn in one form or another, I'm adding HCl to try to convert it back to ZnCl2.
[Edited on 12-3-2005 by LUEshi is my god]
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Jome
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What happens when the material is put into a flame or treated with a base?
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LUEshi is my god
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Heating a small sample of the material in the flame of my zippo caused it to melt and decompose, giving off an odorless grey/black smoke. Dissolving a
small quantity (5g) of the brown solid in water and adding 6g sodium bicarbonate produces a white, crystalline precipitate - possibly zinc hydroxide.
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unionised
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Are you sure there was any real chemistry involved?
The solvation energy of ZnCl2 and/ or HCl by methanol is likely to be large, possibly enough to boil the methanol.
The mystery liquid boiling at a bit over 100C might be HCl(aq)
Brown discolourations could come from any junk present, dust might be enough to do the job.
How pure were the starting materials?
[Edited on 16-3-2005 by unionised]
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LUEshi is my god
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Well, that explains it then. I didn't think about solvation being THAT exothermic, but the discoloration is still puzzling - the methanol was gas
line antifreeze, which when distilled to check, seems to be pure, and the ZnCl2 was prepared by dissolving zinc metal (Sold for use in alloying,
supposed to be >99% pure) in muriatic acid. The discoloration was not present at all before the spill - so could not be in the HCl or Zn - and
there seems to be nowhere icontaminants could enter the mix, unless the gas line antifreeze contains some impurity that boils at the same temp as
methanol. The brand of the antifreeze was "HEET", in case anyone wants to try to reproduce this.
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