# How is partial pressure of oxygen measured?

Jul 30, 2016

The “partial pressure” of any gas in a mixture can only be inferred from the analysis of the mixture composition.

#### Explanation:

Direct measurement of a pure gas pressure at any given temperature and volume will give you the “partial pressure” for that gas in any other mixture at that temperature and volume.

Partial pressure is found by Dalton's Law:
${P}_{x} = {P}_{T o t a l} \left({n}_{x} / {n}_{T o t a l}\right)$
where
${P}_{x}$ = partial pressure of gas x
${P}_{T o t a l}$ = total pressure of all gases
${n}_{x}$ = number of moles of gas x
${n}_{T o t a l}$ = number of moles of all gases
and, n = PV/RT from the ideal gas laws.