# What volume is occupied by 0.963 mol of CO_2 at 300.9 K and 913 mmHg?

Aug 11, 2016

$V = \frac{n R T}{P}$ $\cong 20 L$
The only difficulty in solving this problem is getting the appropriate units. The quoted units of pressure are unfortunate. We know that $1$ $a t m$ $\equiv$ $760 \cdot m m \cdot H g$; i.e. that $1 \cdot a t m$ will support a column of mercury $760 \cdot m m$ high. Thus $P$ $=$ $\frac{913 \cdot m m \cdot H g}{760 \cdot m m \cdot H g \cdot a t {m}^{-} 1}$ $=$ $1.20 \cdot a t m$ (and this measurement should have been quoted in the problem). If you measured pressures with such a mercury column you would end up getting mercury all over the laboratory, so whoever set this question was ignorant, and deserves a bollocking.
$V = \frac{0.963 \cdot m o l \times 0.0821 \cdot L \cdot a t m \cdot {K}^{-} 1 \cdot m o {l}^{-} 1 \times 300.9 K}{1.20 \cdot a t m}$ $=$ ??L