Calculate the mass ( $g$) of propane ($C_3H_8$) in a bottle of $50\;L$ , at $25^oC$, under a pressure of $7.5$ atm.
$n=\frac{m}{M}$ $n$: number of moles $m$: mass $M$: molar mass
$n$ $=$ $\frac{P\cdot V}{R\cdot T}$ $=$ $\frac{7.5\cdot 50}{0.082\cdot 298}\;mol$ $m$ $=$ $n\cdot M$ $=$ $\frac{P\cdot V\cdot M}{R\cdot T}$ $=$ $\frac{7.5\cdot 50\cdot 44}{0.082\cdot 298}$ $=$ $675\;g$
