34 . 05 mL of phosphorus vapours weigh 0.0625 g at 546 .^(@)C and 0.1 bar pressure . What is the molart mass of phosphorus ?

34 . 05 mL of phosphorus vapours weigh 0.0625 g at 546 .^(@)C and 0.1

1.	34 . 05 mL of phosphorus vapours weigh 0.0625 g at 546 .^(@)C and 0.1 bar pressure . What is the molart mass of phosphorus ?
Answer» <P> Solution :ACCORDING to gas EQUATION, `PV = nRT` or `PV =w/M RT` Given : `P = 0.1 " bar," V =340.5 mL = 340.5 xx 10^(-3) dm^3, W = 0.0625 g, R = 0.0831 " bar " dm^3 K^(-1) mol^(-1)` `T = 546^@C = 819 K, M` = ? `:. M=(W.R.T)/(P.V)= (0.0625 xx0.0831 xx 819)/(0.1 xx 340.5 xx 10^(-3))` = `124.92 g mol^(-1)` Hence, molar MASS of phosphorus is `124.92 g mol^(-1)`.