# What is the molar mass of a .250 gas that occupies 1.01 L at 31°C and 1.44 atm?

Jun 13, 2016

Approx. $4.3 \cdot g \cdot m o {l}^{-} 1$.

#### Explanation:

We assume Ideal Gas Behaviour, by which we can calculate a molar mass:

$\text{Mass"/"Molar Mass} = \frac{P V}{R T}$

And thus $\text{Molar Mass}$ $=$ $\frac{R T}{P V} \times \text{Mass}$

$=$ $\frac{0.0821 \cdot L \cdot a t m \cdot {K}^{-} 1 \cdot m o {l}^{-} 1 \times 304 \cdot K \times 0.250 \cdot g}{1.44 \cdot a t m \times 1.01 \cdot L}$

$=$ ??

What do you think is the identity of the gas?

And why did I go to the bother of writing out the individual units, pounds, ounces, furlongs, in the calculation? It was to help save me from making an error. I wanted an answer in $g \cdot m o {l}^{-} 1$, and when I cancelled out the common terms, I got such an answer. This persuades me that I am not entirely clueless (only partially clueless today!).