0
$\begingroup$

edit: Thanks Ivan, also further research.

Pure water can be superheated to a few degrees above 100 degrees. However I remember reading reading that water can be superheated to even higher temperatures by covering it in a thin layer of oil that more effectively prevented the water from boiling. When disturbed the water can then suddenly boil and vaporise at a very fast rate. Apparently a microwave is an effective way to heat the water for this purpose.

However this can easily become very dangerous.

As liquid nitrogen boils at -196 degrees C, would using liquid nitrogen instead, with a thin layer of oil allow the same suppression of boiling, superheating, and sudden vaporisation to be observed but at much safer temperatures, as well as keeping the liquid nitrogen in it's liquid state at higher temperatures?

See also: physics.stackexchange.com/questions/29392/why-droplets-of-water-under-oil-explod‌​e-when-heated

Improve this question
$\endgroup$
4
  • 3
    $\begingroup$ Oil does not really matter much; you can pretty well superheat water without any oil. But in any case, you can superheat a liquid only by a few degrees, not hundreds. So superheated liquid nitrogen would look and behave pretty much like ordinary liquid nitrogen, which is not all that spectacular. Also, I wouldn't call it totally safe (though in most cases it is less harmful than boiling water). $\endgroup$
    – Ivan Neretin
    Commented Jan 15, 2016 at 7:46
  • $\begingroup$ I've just seen that this can be done with only pure water alone. I remember reading that using water and oil the temperature that the water can be superheated to is much higher than 100 degrees, although I don't remember where I saw this information and now cannot find it. I've also found the MythBusters episode on using only pure water, the explosion was a lot less vigorous than I remember reading this can be, there was still a lot of liquid water left and the microwave was fine. See physics.stackexchange.com/questions/29392/why-droplets-of-water-under-oil-explode-when-heated $\endgroup$
    – alan2here
    Commented Jan 15, 2016 at 12:06
  • $\begingroup$ I hope you don't mind if I incorporate this new information into the question. $\endgroup$
    – alan2here
    Commented Jan 15, 2016 at 12:07
  • 1
    $\begingroup$ According to this source, the highest you can metastably heat liquid water at ambient pressure before it boils spontaneously is about 300 ºC, which is actually much higher than I expected. For liquid nitrogen, the upper limit is -163 ºC, only 33 degrees higher than its normal boiling point. $\endgroup$
    – Nicolau Saker Neto
    Commented Jan 16, 2016 at 13:00

1 Answer 1

Reset to default
0
$\begingroup$

Thank you Nicolau Saker Neto.

Superheating is possible up to 300°C for water, yet disappointingly only -163°C for liquid nitrogen.

Source: http://www.nist.gov/data/PDFfiles/jpcrd276.pdf

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.