Given:
refractive index of pure hexane, = 1.375
refractive index of pure hexane, = 1.497
refractive index of mixture, = 1.401
Formula used:
As refractive index here, behaves like a colligative prop. then using the following formula:
(1)
where,
= hexane mole fraction
= toulene mole fraction
+ = 1 (2)
Solution:
Now, using given formula from eqn (1)
(3)
Multiply eqn (2) by 1.375, we get:
+ 1.375\times = 1.375 (4)
Now, solving eqn (3) and (4):
= 0.213
Substituting the value of = 0.213 in eqn (1), we get:
= 1 - 0.213
= 0.787
Therefore, mole fraction of hexane in the sample is = 0.787