Question

calculate the mole fraction of ethanol and water in a sample of restified spirit which contains 95% of ethanol by mass
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Answer 1

Answer:

Mole fraction of ethanol is 0.25. Mole fraction of water is 0.75

Answer 2

Answer:

mole friction of ethanol is 0.25 and mole friction of water is 0.75

Explanation:

Let weight of solution is 100g

∵ mass % of ethanol is 92 %

∴ mass of ethanol in solution = 92g

and mass of water = 100 - 92 = 8g

Now, mole fraction of ethanol = mole of ethanol /(mole of ethanol + mole of water )

Mole of ethanol = mass of ethanol/molar mass of ethanol

= 92/46 = 2 [ ∵ molar mass of ethanol (C₂H₅OH) is 46 g/mol ]

Mole of water = mass of water/molar mass of water

= 8/18 = 4/9 = 0.444

∴mole fraction of ethanol = 2/(2 + 0.444) = 2/2.444 = 0.818