A solution has a 1: 4 mole ratio of pentane to hexane. The vapour pressure of the pure hydrocarbons at 20^ C are 440 mm of Hg for pentane and 120 mm of Hg for hexane. The mole fraction of pentane in the vapour phase would be

Step-by-step solution

Total vapour pressure of mixture = (Mole fraction of pentane VP of pentane ) + (Mole fraction of hexane VP of hexane) = VP of pentane in mixture +VP of hexane in mixture = ( 1 5 440+ 4 5 120 )=184 ~mm VP of Pentane in mixture. = VP of mixture mole fraction of pentane in vapour phase 88=184 mole fraction of pentane in vapour phase Mole fraction of pentane in vapour phase = 88 184 =0.478