# A cylinder is filled with 200 moles of nitrogen, 300 moles of argon, and 5.00 moles of helium. If the gas mixture is at STP, what is the partial pressure of the argon?

Dec 17, 2016

The $\text{partial pressure}$ of any gaseous mixture is simply proportional to its mole fraction.

#### Explanation:

${P}_{\text{Ar"=n_"Ar"/(n_"dinitrogen"+n_"Ar"+n_"He")xxP_"gaseous mixture}}$

$= \frac{300 \cdot m o l}{200 \cdot m o l + 300 \cdot m o l + 5 \cdot m o l} \times 1 \cdot \text{bar}$

$= \frac{300}{505} \times 1 \cdot \text{bar}$

I leave ti to you to decide what is $S T P$. Different syllabus has different requirements.