Editing Partial pressure (section)

==Ideal gas mixtures==
Ideally the ratio of partial pressures equals the ratio of the number of molecules. That is, the [[mole fraction]] <math>x_{\mathrm{i}}</math> of an individual gas component in an [[ideal gas]] [[mixture]] can be expressed in terms of the component's partial pressure or the [[mole (unit)|moles]] of the component:
<math display="block">x_{\mathrm{i}} = \frac{p_{\mathrm{i}}}{p} = \frac{n_{\mathrm{i}}}{n}</math>

and the partial pressure of an individual gas component in an ideal gas can be obtained using this expression:
<math display="block">p_{\mathrm{i}} = x_{\mathrm{i}} \cdot p</math>

{| border="0" cellpadding="2"
|-
|align=right|where:
|&nbsp;
|-
!align=right|<math>x_{\mathrm{i}}</math>  
|align=left|= mole fraction of any individual gas component in a gas mixture
|-
!align=right|<math>p_{\mathrm{i}}</math>
|align=left|= partial pressure of any individual gas component in a gas mixture
|-
!align=right|<math>n_{\mathrm{i}}</math>
|align=left|= moles of any individual gas component in a gas mixture
|-
!align=right|<math>n</math>
|align=left|= total moles of the gas mixture
|-
!align=right|<math>p</math>
|align=left|= total pressure of the gas mixture
|}

The mole fraction of a gas component in a gas mixture is equal to the volumetric fraction of that component in a gas mixture.<ref>[http://antoine.frostburg.edu/chem/senese/101/gases/ Frostberg State University's "General Chemistry Online"]</ref>

The ratio of partial pressures relies on the following isotherm relation:
<math display="block">\frac{V_{\rm X}}{V_{\rm tot}} = \frac{p_{\rm X}}{p_{\rm tot}} = \frac{n_{\rm X}}{n_{\rm tot}}</math>
* ''V''<sub>X</sub> is the partial volume of any individual gas component (X)
* ''V''<sub>tot</sub> is the total volume of the gas mixture
* ''p''<sub>X</sub> is the '''partial pressure''' of gas X
* ''p''<sub>tot</sub> is the total pressure of the gas mixture 
* ''n''<sub>X</sub> is the [[amount of substance]] of gas (X)
* ''n''<sub>tot</sub> is the total amount of substance in gas mixture