In: Chemistry
Ans. Noble gases include –
He – Molar mass = 4.00 g/ mol
Ne – Molar mass = 20.18 g/ mol
Ar – Molar mass = 39.45 g/ mol
Kr – Molar mass = 83.80 g/ mol
Xe – Molar mass = 131.29 g/ mol
Rn – Molar mass = 222.0 g/ mol
At STP, 1 mol of all gases (ideal) occupy a volume of 22.414 L/ mol.
# Density of gas at STP = Molar mass / Molar volume at STP - equation 1
Note that, greater is the molar mass of a gas in equation 1, greater would be its density at STP because the molar volume remains constant at 22.414 L/mol
For example-
Density of He = (4.00 g/ mol) / (22.4 L /mol) = 0.1786 g/ L
Density of Kr = (83.80 g/ mol) / (22.4 L /mol) = 3.7411 g/ L
Density of Rn = (222.0 g/ mol) / (22.4 L /mol) = 9.9107 g / mol
Therefore, Rn has highest density at STP.