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From the description of boiling here:

Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapor pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding environmental pressure.

What I do not understand is the last statement. Does this mean that by definition, boiling cannot occur if we have a homogeneous system (i.e. a closed container of liquid water at equilibrium with its vapor phase) since the definition requires an "atmosphere"? Should we still see the nucleation effect or "bubbles" even in the absence of atmosphere (like in a pressure controlled piston-cylinder assembly)? If so, what is the difference in phase transition between presence of atmosphere or no atmosphere?

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The definition does not require an "atmosphere". Your "environment" can be vacuum. A liquid can boil in vacuum.

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  • $\begingroup$ This is what I had thought, but if so how does the last sentence of the Wiki article fit in? Does the presence of an atmosphere have no effect on the boiling mechanism itself (i.e. we will still see nucleation/bbubles even under a pressure controlled homogeneous environment)? $\endgroup$ – Yandle Oct 26 '14 at 4:08
  • $\begingroup$ @Yandle: The presence of atmosphere does have effect on the boiling mechanism, for example, through its pressure. I believe, however, that "we will still see nucleation/bbubles even under a pressure controlled homogeneous environment", as there are vapor bubbles (scienceline.ucsb.edu/getkey.php?key=3197 ) $\endgroup$ – akhmeteli Oct 26 '14 at 4:34
  • $\begingroup$ If I had a piston maintaining 1atm of pressure, how does the mechanism differ than if I boil a pot of water open to 1atm of air? Is there a reason why boiling typically implies the presence of an atmosphere? $\endgroup$ – Yandle Oct 26 '14 at 4:36
  • $\begingroup$ @Yandle: I guess there can be more than one differing factor, but, in particular, the vapor pressure under the piston will always be saturated (in equilibrium). $\endgroup$ – akhmeteli Oct 26 '14 at 4:49
  • $\begingroup$ @Yandle: I guess one "reason why boiling typically implies the presence of an atmosphere" is it is difficult (if not impossible) to achieve full vacuum. $\endgroup$ – akhmeteli Oct 26 '14 at 4:50

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