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.