# What is the pressure of 4 moles of helium in a 50 L tank at 308 K?

Feb 7, 2017

$P \cong 2 \cdot a t m$

#### Explanation:

We assume ideality, and from the Ideal Gas Equation,

$P = \frac{n R T}{V} = \frac{4 \cdot m o l \times 0.0821 \cdot \frac{L \cdot a t m}{K \cdot m o l} \times 308 \cdot K}{50 \cdot L}$

$\cong$ $2 \cdot a t m$.

The difficult part of this equation is to select the appropriate gas constant, with the appropriate units. Fortunately, in any examination, several Gas constants, with a selection of appropriate units, will be supplied.