A sample of an unknown gas weighing 0.144 grams has a volume of 275 mL at 755 mmHg and 97°C. What is the molar mass of the gas?

Question

Ideal law, show work please

Answer 1

The molar mass is the number of grams per number of moles. You were given grams so you need to calculate the number of moles.

The Ideal Gas Law says PV = nRT or

n = PV/(RT)

You can look up "R" (the ideal gas constant) in various units. One is 62.3636 mmHg•L/(mol•K)

P = 755 mmHg

V = 276 mL = 0.275 L

T = 97°C = 370.15 K

n = (755)(0.275)/(62.3636•370.15) = 207.625/23088654 = 0.008994 moles

Molar mass = (0.144 g)/(0.008994 moles) = 16.0 g/mol