# Problem: A sample of gas has a mass of 38.8 mg . Its volume is 226 mL at a temperature of 56 oC and a pressure of 860 torr .Find the molar mass of the gas.

###### FREE Expert Solution

We’re being asked to determine the molecular weight of the unknown gas.

Recall that molecular weight is in grams per 1 mole of a substance.

Step1: First, we have to calculate the amount of gas in moles using the ideal gas equation.

$\overline{){\mathbf{P}}{\mathbf{V}}{\mathbf{=}}{\mathbf{n}}{\mathbf{R}}{\mathbf{T}}}$

P = pressure, atm
V = volume, L
n = moles, mol
R = gas constant = 0.08206 (L·atm)/(mol·K)
T = temperature, K

Isolate n (number of moles of gas):

###### Problem Details

A sample of gas has a mass of 38.8 mg . Its volume is 226 mL at a temperature of 56 oC and a pressure of 860 torr .

Find the molar mass of the gas.