A question I was asked was: "Why is ethanol added to chloroform bottles?". I know that chloroform can be slowly converted to poisonous phosgene gas, and that ethanol is added to prevent phosgene levels from rising. However, the options I was given were:

  • It decomposes phosgene by converting it into ethyl carbonate.
  • It removes phosgene by converting it into ethyl carbonate

Is there a difference between the two wordings, and is one more correct than the other? The answer is supposedly "decomposes".

  • 1
    $\begingroup$ I won't say it decomposes. It either converts to ethyl carbonate or all the phosgene gets consumed to form ethyl carbonate. So, for me, it should be "it removes phosgene". $\endgroup$ Commented Jun 11, 2019 at 2:26
  • $\begingroup$ Wanted to comment but the comment by Nilay Ghosh already gives the answer. en.m.wikipedia.org/wiki/Chemical_decomposition $\endgroup$
    – Alchimista
    Commented Jun 11, 2019 at 11:02

1 Answer 1


It's a weird way of phrasing it, but I think they are trying to lead you to this

Basically, chloroform is stabilized with ethanol or amylene, but if a sample is dried, it will no longer contain stabilizer. To actually remove phosgene, you can wash it with NaHCO3. This would essentially leave you with entirely harmless products.

This is my best guess as to what they are trying to get you to understand. Please let me know if this helps.

  • 3
    $\begingroup$ What's your stance? Which option are you suggesting? $\endgroup$ Commented Jun 11, 2019 at 2:44

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