Given,
p = 0.1 bar
V = 34.05 mL = 34.05 × 10−3 L = 34.05 × 10−3dm3
R = 0.083 bar dm3K−1mol−1
T = 546°C = (546 + 273) K = 819 K
From the gas equation PV = w. RT / M, we get
M = w. RT/ Pv ……….
(1)The molar mass of phosphorus, M=wRTPV=0.0625×0.08314×8191×34.05×10−3=124.46g/mol.