Suppose you have been given the task of distilling a mixture of hexane + toluene. pure hexane has a refractive index of 1.375 and pure toluene has a refactive index of 1.497. you collect a distillate sample which has a refractive index of 1.456. assuming that the refractive index of the hexane + toluene mixture varies linearly with mole fraction, what is the mole fraction of hexane in your sample?

Explanation:

The given data is as follows.

         Refractive index of mixture = 1.456

        Refractive index of hexane = 1.375

        Refractive index of toulene = 1.497

Let mole fraction of hexane =

and, mole fraction of toulene =

Also,        

or,            

Hence, calculate the mole fraction of hexane as follows.

        refractive index mixture= mole fraction hexane × ref index hexane + mole fraction toluene × ref index toluene.

              1.456 =

               1.456 =

               0.081 =

                    =

                                = 0.66

Since,    

                          = 1 - 0.66

                          = 0.34

Thus, we can conclude that mole fraction of hexane in your sample is 0.34.