Determining mole fraction of water in mixture

Question

A mixture has 18 g water and 414 g ethanol. What is the mole fraction of water in mixture (suppose ideal behaviour of mixture): (i) 0.1  (ii) 0.4  (iii) 0.7  (iv) 0.9

Choose the right answer from above.

Answer 1

The right answer is (a)

Molecular weight of C₂H₅OH = 24+5+16+1= 46
Molecular mass of H₂O = 18
414g of C₂H₅OH has 414/ 46= 9 mole
18g H₂O has 18/18 = 1 mole
Mole fraction of water = n1/ n1 + n1 = 1 / 1+9 = 1 / 10 = 0.1