Q.
At 300K the vapour pressures of two pure liquids. A and B are 100 and 500 mm Hg, respectively. If in a mixture of A and B, the vapour pressure is 300mmHg, the mole fractions of A in the liquid an d in the vapour phase, respectively are
In liquid phase, according to Dalton’s law of partial pressure PT=PA+PB =xApA∘ + xBpB∘ =xApA∘+(1−xA)pB∘ PT=(pA∘−pB∘)xA+pB∘ 300=(−400)xA+500 xA=21
In vapour phase, xA=pTpA=p∘AxA+p∘BxBp∘AxA =100×21+500×21100×21 =30050=61