# An experiment shows that a 248-mL gas sample has a mass of 0.433 g at a pressure of 745 mm Hg and a temperature of 28°C. What is the molar mass of the gas?

May 31, 2018

$\text{Molar mass} \cong 100 \cdot g \cdot m o {l}^{-} 1$

#### Explanation:

$P V = n R T = \text{mass"/"molar mass} R T$

And thus $\text{molar mass} = \frac{R T}{P V}$

And so here....$\text{molar mass} = \frac{0.0821 \cdot \frac{L \cdot a t m}{K \cdot m o l} \times 301.1 \cdot K}{\frac{745 \cdot m m \cdot H g}{760 \cdot m m \cdot H g \cdot a t {m}^{-} 1} \times 0.248 \cdot L}$

=??*g*mol^-1

The key idea of this problem was the recognition that $760 \cdot m m \cdot H g \equiv 1 \cdot a t m$...and thus a unit of length was proportional to a unit of pressure....