Answer:
We are given that there is 95% ethanol by mass in rectified spirit
so, we can say that in a 100g sample, we have 95 grams of ethanol and 5 grams of water
we will find the number of moles of ethanol and water in 100g solution of rectified spirit and use that to calculate the mole fraction
Moles of Ethanol:
Molar mass of ethanol = 46 grams / mol
Number of moles = Given mass / molar mass
Number of moles = 95 / 46
Moles of Ethanol = 2 moles (approx)
Moles of Water:
Molar mass of water = 18 grams per mol
Number of moles = Given mass / molar mass
Moles of water = 5 / 18
Moles of water = 0.28 moles (approx)
Mole Fractions:
Mole fraction of a specific compound is the number of moles of that compound divided by the total number of moles in the solution
Mole fraction of Ethanol:
Moles of ethanol / (moles of ethanol + moles of water)
2 / (2 + 0.28)
2 / (2.28) = 0.9 (approx)
Mole fraction of Water:
Moles of water / (Moles of ethanol + moles of water)
0.28 / (2 + 0.28)
0.28 / (2.28) = 0.1 (approx)