The term Mole Fraction of substance A in a mixture of A and B means

(select ALL the correct definitions)

The fraction of the molecules present which are A
The number of moles of A divided by the number of moles of A plus the number of moles of B
The number of moles of A divided by the number of moles of B
The fraction of the amounts in moles of the two substances which is A
The number of moles of A in a gramme of mixture
The number of moles of A in a litre of mixture

Some posh Scotch whiskys contain 43% by volume alcohol. Such a solution in fact contains 36g alcohol per 100g of solution. Given that M_r for alcohol is 46.1 g.mol^-1, calculate the mole fraction of alcohol in such a mixture. Assume the mixture contains only alcohol and water.

Give your answer to TWO decimal places

Calculate x_A in wine if a sample of 200g contains 17 g alcohol (10.5%v/v)

(again C₂H₅OH = 46.1)

Give your answer to TWO significant figures - remember that preceding zeros do not count towards the number of significant figures.

Motor antifreeze is mainly a solution of ethylene glycol (1,2-dihydroxyethane, M_r 62.07) in water.
Calculate the mole fraction of a 25 % solution, by weight, i.e.100g solution contains 25 g glycol.

Golden syrup is 85% sugars and 15% water approximately. Assuming the sugars are sucrose (C₁₂H₂₂O₁₁, M_r 342.3), calculate the mole fraction of sucrose.

Give your answer to TWO decimal places

Calculate the mole fraction of water in the golden syrup

Give your answer to TWO decimal places

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