Question

22 mm of Hg respectively
The vapour pressure of benzene and toluene at 20°C are 75 mm of Hg and 22 mm
234 g of benzene and 64.4g of toluene are mixed. If two forms ideal solution, the mole fracti
vapour phase when vapours are in equilibrium with liquid mixture, is -
1.) 0.53,0,41
(B)0.25, 0.75
(C)0,5, 0,5
(D) 0.35, 0.65
on of benzenes​

Answer 1

molar weight of benzene = 78

moles of benzene in 234    =  234/78

                                             = 3 mol

toluene molecular weight =  92

  moles of toluene in 64.4 g  = 64.4/92

                                  =0.7

total mole = 3+0.7  

               = 3.7

let 1 be benzene , 2 be toluene

x1 (mole fraction of benzene)  = mole benzene / total mole

                                           = 3/3.7

                                          = 0.81

x2 = 0.19

Pt= P1 x1 + P2 x2

= 75*.81+ 22 * .19

=64.93

y1 Pt= P1x1

y1 = 75*.81 / 64.93

  = 0.93