Editing Ideal gas (section)

=== Ideal gas law ===
{{ideal_gas_law_relationships.svg}}
{{main|Ideal gas law}}

The [[ideal gas law]] is the equation of state for an ideal gas, given by:
<math display="block" qid=Q11432>PV = nRT</math>
where
* {{mvar|P}} is the [[pressure]]
* {{mvar|V}} is the [[Volume (thermodynamics)|volume]]
* {{mvar|n}} is the [[amount of substance]] of the gas (in [[Mole (unit)|moles]])
* {{mvar|T}} is the [[absolute temperature]]
* {{mvar|R}} is the [[gas constant]], which must be expressed in units consistent with those chosen for pressure, volume and temperature. For example, in [[SI Units|SI units]]  {{mvar|R}} = 8.3145&nbsp;[[joule|J]]⋅[[kelvin|K]]<sup>−1</sup>⋅[[mole (unit)|mol]]<sup>−1</sup> when pressure is expressed in [[pascals]], volume in cubic [[meters]], and absolute temperature in [[kelvin]]. 

The ideal gas law is an extension of experimentally discovered [[gas laws]]. It can also be derived from microscopic considerations.

Real [[fluid]]s at low [[density]] and high [[temperature]] approximate the behavior of a classical ideal gas. However, at lower temperatures or a higher density, a real fluid deviates strongly from the behavior of an ideal gas, particularly as it [[Condensation|condenses]] from a gas into a liquid or as it [[deposition (phase transition)|deposits]] from a gas into a solid.  This deviation is expressed as a [[compressibility factor]].

This equation is derived from
* [[Boyle's law]]: <math>V\propto\frac{1}{P}</math>;
* [[Charles's law]]: <math>V\propto T</math>;
* [[Avogadro's law]]: <math> V \propto n</math>.
After combining three laws we get
: <math>V \propto \frac{nT}{P}</math>
That is:
: <math>V = R\left(\frac{nT}{P}\right)</math>
: <math>PV = nRT</math>.