Need explanation why water in a vacuum chamber at first boils and than freeze, I would appreciate if you can base your explanation on chart of enthalpy/pressure/temperature.
best regards
Tzur.
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Need explanation why water in a vacuum chamber at first boils and than freeze, I would appreciate if you can base your explanation on chart of enthalpy/pressure/temperature.
best regards
Tzur.
Simple.:cool:Quote:
Originally Posted by tzur
Because, in vacuum, water evaporates. When something evaporates, it need heat to change state (basic to our cooling processes). So, evaporating water removes heat from surrounding and cools it. That is why remaining water freezes.
Using the power of Google, instead of my brain, I found this...
http://www.newton.dep.anl.gov/askasc.../chem99558.htm
OK, thanks both of you, according to that explanation I would expect that when water stops boiling its temp would stay steady at around 273k. According to my experience temperature of the solid ice decreasing more with the decreasing of pressure, I measured 245k; I'm looking for some relation between pressure and temperature.
Thanks,
Tzur.
Quote:
Originally Posted by tzur
-water needs heat to boil
-if you lower the pressure, the amount of heat needed to boil decreases.
-if you lower the pressure to fast, heat cant transfer fast enough and the water freezes