What is the vapour pressure of solution prepared by mixing 25.5 g of CHCl3 and 40 g of CH2Cl2 at 298 K?

Molar mass of CH2Cl2=12×1+1×2+35.5×2                                        =85gmol−1 Molar mass of CHCl3=12×1+1×1+35.5×3                                      =119.5gmol−1             Moles of CHCl3=25.5119.5=0.213mol           Moles of CH2Cl2=40g85gmol−1=0.47mol Total number of moles =0.47+0.213=0.683mol                           xCH2Cl2=0.47mol0.683mol=0.688  xCHCl3=1.00−0.688=0.312Using equation,   ptotal =p1∘+p2∘−p1∘x2         =200+(415−200)×0.688         =200+147.9         =347.9mmHg