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What is the mole fraction of water in 200g of 95 ethanol?

User Dude Bro
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1 Answer

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If the solution is 95% by weight, that means that in 100 grams of solution you have 5 grams of water and 95 grams of ethanol.

Convert each of these masses to moles by dividing each mass by the molar mass of the compound.

5 g/18 g/mol = 0.278 mol water
95 g / 46g/mol = 2.065 mol ethanol

Mole fraction water:
= mol water / total moles
= 0.278/ (0.278 + 2.065)
= 0.119
User TehOne
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