# What is the pressure in a 19.3-L cylinder filled with 16.7 g of oxygen gas at a temperature of 319 K?

$P = \frac{n R T}{V} \cong 0.70 \cdot a t m$
$\frac{\frac{16.00 \cdot g}{32.00 \cdot g \cdot m o {l}^{-} 1} \times 0.0821 \frac{L \cdot a t m}{K \cdot m o l} \times 319 \cdot K}{19.3 \cdot L} \cong 0.70 \cdot a t m$
Why did I have to divide the mass of the oxygen gas by $32$?