Q.4. The vapour density of a gas is 11.2. Calculate the volume occupied by 11.2 g of the gas at NTP.
[Hint: Mol. wt. = 2VD]
As we know,
molecular wt. = 2 x vapour density = 2 x 11.2 = 22.4g
now, no. of moles present in 1g of of the gas = mass of the gas/molar mass = 1g/22.4g = 0.05 moles (approx)
1 mole of any gas occupies 22.4L volume at STP.
therefore, volume occupied by 1 mole of the gas at ST = 22.4L
and the volume occupied by 0.05 moles of the gas at STP = 22.4L x 0.05 = 11.2 L OR 11.2 L x 1000 =11200 cm3
so the volume occupied by 1g of the gas at STP = 11.2 L OR 11200 cm3.