Question

"X" gm of water mixed with 69 gm of ethanol . The mole fraction of ethanol in the resulting solution is 0.6 . What bis the value of " x" in gm

Answer 1

Explanation:

Molecular weight of ethanol (C₂H₅OH) = (12 × 2) + (1 × 5) + (16 × 1) + (1×1) = 46

No. of moles of ethanol = Given weight/Molecular Weight = 69/46 = 3/2 = 1.5

Mole fraction of water in the resulting solution = 1 - 0.6 = 0.4

Let the no. of moles of water be n.

∴Mole fraction of water = No. of moles of water/Total no. of moles

=> 0.4 = (n/n + 1.5)

=> 0.4n + 0.6 = n

=> n - 0.4n = 0.6

=> 0.6n = 0.6

=> n = 1

∴Mass of water (x) = n × molecular weight of water = 1 × 18 = 18 gm