Ethylene dibromide (C_(2)H_(4)Br_(2))and 1, 2 - dibromo propane from a series of ideal solutions over the whole range of composition. At 85^(@)C, the vapour pressure of these two liquids are 173 and 127 torr respectively. What would be the mole fraction of ethylene dibromide in a solution at 85^(@)C equilibrated with 1:1 molar mixture in the vapour?

Ethylene dibromide (C_(2)H_(4)Br_(2))and 1, 2 - dibromo propane from a

1.	Ethylene dibromide (C_(2)H_(4)Br_(2))and 1, 2 - dibromo propane from a series of ideal solutions over the whole range of composition. At 85^(@)C, the vapour pressure of these two liquids are 173 and 127 torr respectively. What would be the mole fraction of ethylene dibromide in a solution at 85^(@)C equilibrated with 1:1 molar mixture in the vapour?
Answer» Solution :Suppose the mole fraction of ethyene dibromide in the liquid phase = x. Then mole fraction of 1, 2- dibromo PROPANE will be `=1-x`. Vapour pressure of ethylene dibromide `=x xx p^(@)=x xx"173 TORR = 173 x torr"` Vapour pressure of 1, 2- dibromo propane `=(1-x)xx"127 torr"` As they have `1:1` molar ratio in the vapour phase, `173x=(1-x)xx127 or 173x=127-127x or 300x=127 or x=(127)/(300)=0.423.`