User:Milton Beychok/Sandbox: Difference between revisions

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==The meaning of gas or vapor==


There is no significant physical or chemical difference between a gas and a vapor. However, the words have slightly different connotations and there is often considerable overlap between the  connotations, so precise distinctions are not necessary and probably not even possible.<ref>[http://www.chem.queensu.ca/people/faculty/mombourquette/FirstYrChem/slg/index.htm  Lecture by Professor Michael Mombourquette, Queens University Canada]</ref><ref>{{cite book|author=Richard W. Miller|title=Flow Measurement Engineering Handbook|edition=Third Edition|publisher=McGraw-Hill|year=1996 |pages=page 2.1|id=0-07-042366-0}}</ref><ref>[http://www.av8n.com/physics/vapor.htm The Meaning of Vapor, Gas, Fluid] by Dr. John Denker</ref><ref>[http://www.encyclopedia.com/doc/1E1-vaporiza.html Vaporization: Columbia Encyclopedia, 6th Edition, 2008]</ref>
Almost all [[physics]], [[chemistry]] and [[engineering]] textbooks refer to the [[states of matter]] as [[solid]], [[liquid]], gas and [[plasma]]. Rarely, if ever, do the states of matter include ''vapor'' rather than ''gas''.
One way in which the word ''vapor'' sometimes replaces the word ''gas'' is when the gaseous phase is in [[equilibrium (chemistry)|equilibrium]] with the corresponding liquid or solid. We call the [[pressure]] of the gas phase in equilibrium with the corresponding liquid phase ''[[vapor pressure]]''. We connote the equilibrium of the gas and liquid phases of a substance as ''[[vapor-liquid equilibrium]]''. But note that all of the connotations are defined as the equilibrium between a gas phase and a liquid phase.
The [[boiling point]] of a liquid may be defined as the [[temperature]] at which it changes its state of matter from a liquid to a gas, but we connote that phase change as ''[[vaporization]]''. We also connote the heat required to change a liquid into a gas as the ''[[heat of vaporization]]''.
Then there are definitions like: ''a vapor is the gaseous form of a liquid'', ''the word vapor describes the gaseous state of a substance'' and ''water vapor is the most important [[greenhouse gas]].
It is not the intent of this section to deter anyone from using any of the above connotations. However, it is the intent of this section to make the point that there is no physical or chemical difference between a gas and a vapor and the words may be used interchangeably.
==References==
{{reflist}}
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Revision as of 22:52, 24 June 2008

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