Question

Calculate the relative molecular mass and vapour density of methyl alcohol if 160g of the alcohol on vaporization has a volume of 112 litres at s.t.p.

Answer 1

112 litres of methyl alcohol vaporized from 160g

1 litre of methyl alcohol needs how many grams = 160/112=1.428 g at STP

1 litre of hydrogen at STP weighs 0.09g

Vapour density of methyl alcohol = Mass of 1 litre of Methyl alcohol/ Mass of 1 litre of    hydrogen

VD = 1.428/0.09 = 15.86 ≈ 16

Relative Molecular Mass = 2 X VD =2 X 15.86 =31.73 g ≈32 g