# A tank contains helium gas at 490 mmHg, nitrogen 0.75 atm, and neon at 520 torr. What is the total pressure in atm?

Dec 9, 2016

Well, we turn the measurements of pressure into $\text{atmospheres}$, and get...........
${P}_{\text{He"+P_(N_2)+P_"Ne}} =$
$\frac{490 \cdot m m \cdot H g}{760 \cdot m m \cdot H g \cdot a t {m}^{-} 1} + 0.75 \cdot a t m + \frac{520 \cdot m m \cdot H g}{760 \cdot m m \cdot H g \cdot a t {m}^{-} 1} \cong 2 \cdot a t m .$
You know that $1 \cdot a t m \equiv 760 \cdot m m \cdot H g$. Or rather that one atmosphere will support a column of mercury $760 \cdot m m$ high. You must simply know this. This measurement of pressure should not really be used above $1 \cdot a t m$.