Question

A 0.479 g sample of nitrogen, oxygen or neon gas occupies a volume of 265 ml at 157 kpa and 20◦c. what is the molar mass and identity of the gas?

Answer 1

PV = nRT
P = 157 kPa = 157 × 10³ Pa
V = 265 ml = 0.265 l
T = 20°C = 293 K
m = 0.479 g
PV•M = mRT
M = (mRT)/(PV)
M = 0.479 g × 8.314 kPa.l/(mol.K) × 293 K / (157 kPa × 0.265 l)
M ≈ 28.04579 g/mol.
Hence, the Molar Mass of Dinitrogen or Nitrogen Gas is 28 g.