To identify the contents of an unlabelled cylinder of gas,a sample was collected and found to have a density of - Chemistry - States of Matter

Question

To identify the contents of an unlabelled cylinder of gas,a
sample was collected and found to have a density of 5 380g/L at 15
degreesC and 736mm Hg pressure what is the molar mass of the
gas?

Arti Gujrati · Accepted Answer

Use the ideal gas equation : PV = nRT
n (number of moles) = m (given mass)/ Molar mass (M)
PV = (m/M)RT
Or,
M= mRT/PV (1)
â€‹m/V = Density D , so eq (1) can be written as
:
M = DRT/P (2)
Now we have to calculate the gas constant R in term of mm Hg
pressure using the formula given below
R= PV/nT
R = 760 mmHg x 22 4L / 1 mole x 273 K = 62 4 mm Hg L/ mole K
T = 15 º C = (15+273) K = 288 K
D = 5 38 g/L

Putting the values in eq(2) we get :
M = 5 380 g / L x 62 4 mm Hg L/mole K x 288 K / 736 mm Hg = 131 4 g
/ mole

The Molar mass of unknown gas is 131 4 g/mole

To identify the contents of an unlabelled cylinder of gas,a sample was collected and found to have a density of 5.380g/L at 15 degreesC and 736mm Hg pressure.what is the molar mass of the gas?