# How is the partial pressure of a component gas proportional to the percentage composition (by molar quantity) to the gaseous mixture?

Feb 14, 2017

The partial pressure of each gas is proportional to the given percentage.

#### Explanation:

${P}_{\text{Total"=P_"methane"+P_"ethane"+P_"propane"+P_"butane}}$.

Given the Ideal Gas equation, P_"Total"=(n_"Total"RT)/V

But n_"Total"=(n_"methane"+n_"ethane"+n_"propane"+n_"butane")

And so,

P_"Total"=(n_"methane"+n_"ethane"+n_"propane"+n_"butane")(RT)/V

You have the percentage composition of the gas, and you simply multiply ${P}_{\text{Total}}$ by the individual percentages to get the partial pressure of each gas.

Thus P_"methane"=1.48*atmxx94%=??*atm. And you can work out these pressures individually.

See here for another example.