This question (Is there a chemical that when added to water makes the water flash evaporate?) was posted 2 days ago, closed yesterday as being too broad and reopened today (14th Sep 2016 at 17:45Z, timeline). The question has never been edited so its contents are the same throughout.

I wonder why people voted to reopen it and why that vote subsequently went through. The question asks whether there is a chemical that can be added to water so that it will instantly flash evaporate. In my opinion, there are hundreds.

  • dropping sulphuric acid into water will make part of it evaporate quickly.
  • pouring liquefied salts into water will transfer large amounts of heat; some will cause explosive evaporation.
  • Loong mentioned an enriched uranium salt that will induce a chain reaction in water.
  • the answer it has is an azeotrope idea.
  • I’m pretty sure that some tert-butyllithium will do the trick as well.

There is no constraint either visibly in the question or otherwise that would limit this question to a smaller number of answers. As such, I think it is far too broad and should have remained closed. I am very interested which arguments the reopen voters applied to reopen the question?

Note: Of course I am biased. I am one of the five who closed it in the first place.

  • 4
    $\begingroup$ Indeed, while it was a nice diversionary out-of-the box thought exercise, there clearly is not a single (or safe) answer. It is basically wants a long list of answers, which SE is really not suited for. $\endgroup$
    – Jon Custer
    Sep 14, 2016 at 18:33
  • 3
    $\begingroup$ The silence is deafening :) $\endgroup$ Sep 18, 2016 at 3:27

1 Answer 1


Having been the deciding vote on this, I'd like to expand a little on my reasoning.

While I can see that the question could be considered broad, there is an interesting concept behind it. Additionally it does not ask for a list of chemicals that do the trick - that was something that came up in them damn comments all by itself - but rather if it was possible at all. As such I do not consider this question broad at all; also all them funny comments suggested already that it is possible.

Additionally the question had already received an upvoted answer; it wasn't going anywhere.


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