Vapour density of a gas, relative to air is 1.528. what is the mass of 2L of the gas at 27^(@)C temperature and 750 mm Hg pressure? [vapour density of air, relative to hydrogen=14.4]

Vapour density of a gas, relative to air is 1.528. what is the mass of

1.	Vapour density of a gas, relative to air is 1.528. what is the mass of 2L of the gas at 27^(@)C temperature and 750 mm Hg pressure? [vapour density of air, relative to hydrogen=14.4]
Answer» Solution :Vapour density of a gas`=("mass of certain volume of a gas")/("mass of same volume "H_(2)" gas ")` [at certain temperature and pressure] `therefore`Vapour density of the gas `=("mass of V "cm^(3)" of gas")/("mass of V "cm^(3)" of air")xx("mass of V "cm^(3)" of air")/("mass of V "cm^(3)" off "H_(2)" gas")` [at the same temperature and pressure] `=1.528xx14.4=22` `therefore`Molecular mass of the gas=`2xx`vapour density=44 Again, volume of 1 gram-mole of any gas at STP=22.4 L So, mass of 22.4L of given gas at STP=44g Now, let the volume of the gas be V L at STP. i.e., `P_(1)=750mm,P_(2)=760mm,V_(1)=2L,V_(2)=VL,` `T_(1)=27^(@)C=(27+273)=300K,T_(2)=273K` `therefore (760xx2)/(300)=(760xxV)/(273) or, V=(750xx2xx273)/(300xx760)=1.796L` Now, mass of 22.4 L of the gas at STP=44g. `therefore`Mass of 1.796g of the gas at STP`=(44xx1.796)/(22.4)=3.528g` HENCE, the mass of the gas =3.528g.