# Question #32af4

Dec 7, 2014

The answer is $132.5 \frac{g}{m o l}$.

This is a pretty straighforward application of the ideal gas law, $P V = n R T$. In order to determine the gas' molar mass, we must first determine the number of moles for this particular set of paramaters:

${n}_{g a s} = \frac{P V}{R T} = \frac{\left(\frac{743}{760}\right) \cdot 109 \cdot {10}^{- 3}}{0.082 \cdot 358.15} = 0.004$ moles

Notice how pressure was converted to atmospheres, volume to liters and temperature to K.

Therefore, the gas' molar mass is equal to

$m o l a r m a s s = {m}_{g a s} / {n}_{g a s} = \frac{0.530 g}{0.004 m o l e s} = 132.5 \frac{g}{m o l}$