Question

The vapor pressure of pure benzene (C6H6) at 25°C is 94.4 torrwhile the vapor pressure of pure
chloroform (CHCl3) at 25°C is 172 torr. An ideal solution isformed when 50 g of chloroform is added to 50 g
of benzene. Calculate the vapor pressure of chloroform over thischloroform-benzene solution at 25°C.

a) 86 torr
b) 68 torr
c) 148 torr
d) 125 torr
e) 172 torr

Answer 1

   

          

        

    

    

    

  Number of moles of benzene , n = (50 /78) = 0.6410

   Number of moles of chloroform, N = (50 / 119.5) = 0.4184

    

         molefraction of chloroform, X = (0.4180) / (0.4180 +0.6410)

                                                        = 0.3947

         Pressure of Chloroform over the solution =  0.3947 x (pressure of pure chloroform)

                                                                        = 0.3947 x 172 torr

                                                                          =67.9 torr

          ∴ The answer is a)