Refractive index problem help?

Question

Mixtures of acetic acid (nD= 1.3718) and cetyl acetate (nD=1.4358) produce a linear relationship between refractive index and mole fraction. What would be the RI of a compound that would seem to disappear when placed in a solution containing 0.152 mole fraction of acetic acid? Pls pls show me how to get the answer of 1.4261 TNX!

Answer 1

It is basically saying that if the solution is half and half, the RI will be the average of the two.  If it is 25/75, then it will be 25% of the first one's and 75% of the second.

The mole fraction of .152 if 15.2% of the total solution.  The other one is 84.8%.  So,

0.152(1.3718) + 0.848(1.4358)= 1.4261