Molar mass of CHCl3=119.5g∕mol Molar mass of CH2Cl2=85g∕mol Moles of CHCl3=
11.95
119.5
=0.1mol Moles of CH2Cl2=
8.5
85
=0.1mol Mole fraction of CHCl3=
0.1
0.2
=0.5mol Mole fraction of CH2Cl2=
0.1
0.2
=0.5mol (Given - Vapour pressure of CHCl3=200mmHg=0.263atm. Vapour pressure of CH2Cl2=415mmHg=0.546atm.)(1atm=760mmHg) ∴P(total)= Mole fraction of CHCl3× (Vapour pressure of CHCl3 ) + Mole fraction of CH2Cl2 ×( Vapour pressure of CH2Cl2 ) =0.5×0.263+0.5×0.546=0.4045 Mole fraction of CHCl3 in vapour form =