34.05 mL of phosphorus vapour weighs 0.0625 g at 546°C

CBSE Class 11 CBSE Class 11 Chemistry
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1

34.05 mL of phosphorus vapour weighs 0.0625 g at 546°C and 0.1 bar pressure. What is the molar mass Of phosphorus?

2

pV = nRT = mRT/M

M = mRT/pV

M = 0.0625 x 0.0821 atm ${{K}^{-1}}$ ${{mol}^{-1}}$ x 819 K / 0.1 x 0.987 atm x 0.03405 L

M = 1250.4 g ${{mol}^{-1}}$