Talk:Vapor

yeow, are we having fun yet? Frobnitzem 13:35, 7 June 2007 (UTC)[reply]

Yeah, I think so. Anyway, I've got a couple of thoughts: First, the terms "fog" and "mist" are used as examples of "vapor". But in fact, fog and mist are both examples of matter (in this case water) in its liquid state, as fine droplets. They may be suggestive of the coincident presence of vapor, but in themselves aren't examples of vapors. Unlike fog and mist, the vapor phase, being a gas, is invisible (at least for water). Second, the claim is made that the term "vapor" is only correct when in equilibrium with a liquid or solid phase. Yet the usage "water vapor" is common even among scientists to refer to that fraction of air which consists of water in its gaseous state, even when not in the presence of, or equilibrium with, any liquid water at all. The presumably correct term "water gas" is never heard. I suspect that this may have historical reasons stemming from the archaic use of the term "water gas" to refer to the element hydrogen, but there is also the use of the term "mercury vapor", even in situations where there is no liquid phase present. Are these just sloppy usage of the term? I suspect not. Any thoughts on whether changes are needed in the text? Or am I being too pedantic? Jeepien 18:05, 13 September 2007 (UTC)[reply]

I have now corrected the definition so that it does not depend on having a liquid present. I have also included Hg vapor as an example, and specified that fog and mist are liquid droplets. Only a year late! Dirac66 (talk) 19:32, 10 October 2008 (UTC)[reply]