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==The meaning of gas or vapor==
==The meaning of gas or vapor==


There is no significant physical or chemical difference between a gas and a vapor. However, in common usage, there are somewhat different connotations. There is often considerable overlap between the two terms and their 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= |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://encarta.msn.com/encyclopedia_761577009/vapor.html Vapor: MSN Encarta]</ref><ref>[http://www.encyclopedia.com/doc/1E1-vaporiza.html Vaporization: Columbia Encyclopedia, 6th Edition, 2008]</ref>
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= |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>


==References==
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.


{{reflist}}
One way in which the word ''vapor'' sometimes replaces the word ''gas'' is when the gaseous phase is in 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 refer to that phase change as "vaporization". We also refer to the heat required to change a liquid into a gas as the ''[[heat of vaporization]]''.


Water vapor is the most important greenhouse gas






When a substance turns changes from a solid or liquid into a gas, the process is called vaporization. The material is said to vaporize or evaporate. Heat of vaporization. Vapor pressure.
==References==
 
 
 
There is no significant physical or chemical difference between a vapor and a gas. This is the most important point. However, the words have slightly different connotations. Remember that these are just connotations. There is sometimes considerable overlap between the terms, so precise distinctions are not necessary and probably not even possible.Any vapor could technically be called a gas, although in many situations this would sound weird or awkward. One way in which a gas can earn the “vapor” appellation is  when the gaseous phase is in equilibrium with the corresponding liquid or solid. We call the pressure of the gas phase in equilibrium with the corresponding liquid phase "Vapor pressure". A liquid that changes phase to a gas is said to " vaporize" rather than to  "gasify".


{{reflist}}




The boiling point of a liquid may also be defined as the temperature at which it changes its state from a liquid to a gas, but we refer to that phase change as "vaporization".






The term vapor is sometimes used in a more extended sense, as identical with gas; and the difference between the two is not so much one of kind as of degree, the latter being applied to all permanently elastic fluids except atmospheric air, the former to those elastic fluids which lose that condition at ordinary temperatures.






Vapor is the gaseous form of  a liquid. Vapor describes the gaseous state of a substance..




Revision as of 21:38, 24 June 2008

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.[1][2][3][4]

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 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 refer to that phase change as "vaporization". We also refer to the heat required to change a liquid into a gas as the heat of vaporization.



References

  1. ↑ Lecture by Professor Michael Mombourquette, Queens University Canada
  2. ↑ Richard W. Miller. Flow Measurement Engineering Handbook, Third Edition. McGraw-Hill, page 2.1. 0-07-042366-0. 
  3. ↑ The Meaning of Vapor, Gas, Fluid by Dr. John Denker
  4. ↑ Vaporization: Columbia Encyclopedia, 6th Edition, 2008











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