User:Milton Beychok/Sandbox: Difference between revisions
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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. | 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]]''. | 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]]. | 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]]. | ||
Revision as of 22:06, 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 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
- ↑ Lecture by Professor Michael Mombourquette, Queens University Canada
- ↑ Richard W. Miller (1996). Flow Measurement Engineering Handbook, Third Edition. McGraw-Hill, page 2.1. 0-07-042366-0.
- ↑ The Meaning of Vapor, Gas, Fluid by Dr. John Denker
- ↑ Vaporization: Columbia Encyclopedia, 6th Edition, 2008