An evacuated glass vessel weighs 50 gm when empty, 148.0 gm filled with a liquid of density 0.98 gm `ml^(–1)` and 50.5 gm when filled with an ideal gas at 760 mm of Hg at 300 K. What is the molecular weight of the gas ?

Answer

`( 123 g//ml )`

Explanation

Mass of liquid `= 148 - 50 = 98 g`
`rArr` Volume of liquid `= (98)/(0.98) = 100 mL=` volume of flask
Mass of gas `=50.5 - 50 = 0.50g`
Now applying ideal gas equation `pV = ((w)/(M)) RT rArr M = (wRT)/(pV) = (0.5 xx 0.082 xx 300)/(1 xx 0.1) = 123 g mol^(-1)`