34.5 mL of phosphorus vapour weights 0.0625g at `546^@C` and 0.1 bar pressure . What is the molar mass of phosphorus?

Explanation

P = 0.1 bar
W = 0.0625 gms
R = 0.083 bar `dm^3 k^(-1) mol^(-1)`
V= 34.05 x `10^(-3)` lit.
T = `546^@ C = 819 K`
Formula:
PV = nRT
` PV = (w)/(M ) RT `
`0.1 xx 34.05 xx 10^(-3) = ( 0.0625 )/(M ) xx (0.0625 )/(M ) xx 0.083 xx 819`
` M= ( 0.0625 xx 0.083 xx 819 )/(0.1 xx 34.05 xx 10^(-3))`
` = ( 0.0625 xx 83 xx 819 )/( 34.05 )`
`=124.77 ` gm // mole