A 1.44-g sample of an unknown pure gas occupies a volume of 0.335 L at a pressure of 1.00 atm and a temperature of 100.0°C. The unknown gas is __________.

Question

Quizplus · Accepted Answer

Using the combined gas law, we can calculate the number of moles of gas present:
P1V1/T1 = P2V2/T2
(1.00 atm)(0.335 L)/(373.15 K) = P2(0.335 L)/(298.15 K)
P2 = 1.22 atm
Then, we can use the ideal gas law to calculate the molar mass, which we can use to identify the gas:
PV = nRT
(1.22 atm)(0.335 L) = n(0.08206 L atm/mol K)(298.15 K)
n = 0.0142 mol
Molar mass = (1.44 g)/(0.0142 mol) = 101.45 g/mol
The closest match on the periodic table is xenon, which has a molar mass of 131.29 g/mol. Therefore, the unknown gas is likely xenon.

A 144-G Sample of an Unknown Pure Gas Occupies a Volume