Question

How can I find partial pressure given moles?

Answer 1

Partial pressure is defined as the hypothetical pressure of a gas that is part of a mixture of gases that occupy a certain volume and a certain temperature, if that respective gas would occupy the same volum of the mixture, at the same temperature as the mixture.

Now, the mole fraction on an individual gas A that is a component of an ideal gas mixture can be expressed using either the moles of this component, or its partial pressure

`X_A = n_A/n_(TOTAL) = P_A/P_(TOTAL)`, where

`n_A` represents the number of moles of gas A present in the mixture;
`n_(TOTAL)` represents the total number of moles present in the mixture;
`P_A` represents A's partial pressure;
`P_(TOTAL)` represents the total pressure of the gas mixture.

Therefore, a gas' partial pressure can be determined from its moles by knowing the total number of moles of the gaseous mixture and its total pressure

`P_A = n_A/N_(TOTAL) * P_(TOTAL)`