Ethanol is commonly referred to simply as alcohol or spirits, It is the principa

Question

Ethanol is commonly referred to simply as alcohol or spirits, It is the principal type of alcohol found in alcoholic beverages. It is a psychoactive drug and one of the oldest recreational drugs used by humans. It can cause alcohol intoxication when consumed in sufficient quantity. It is a volatile, flammable, colorless liquid with the structural formula CH3CH2OH. The density of an aqueous solution containing 45 weight percent ethanol is 0.92472 g/mL.

a) Calculate the molality of this 45 weight-% solution

b) Calculate the molarity of this 45 weight-% solution

c) What volume of the solution would contain 0.250 mol of ethanol.

d) A person weighing 75 kg takes a swallow of an alcoholic beverage corresponding to 25 gram of pure ethanol. It is assumed that the alcohol mixes evenly in person´s water phase, constituting 62 % of the person´s weight. Calculate the person´s ethanol mass per mille (alkoholpromille in Danish).

e) The vapor pressures of ethanol (C2H5OH) and 1-propanol (C3H7OH) at 35 oC are 100.0 mmHg and 37.6 mmHg, respectively. Assume ideal behaviour and calculate the partial pressures of ethanol and 1-propanol at 35 oC over a solution of ethanol in 1- propanol, in which the mole fraction of ethanol is 0.200.

Explanation / Answer

Ethanol

a) molality = moles/kg of solvent

moles = grams/molar mass

mass of solvent = 1000 - 450 = 550 g

molality = 450/46.07 x 0.550 = 17.76 m

b) molarity of solution

= moles/L of solution,

Volume of solution = 1000 g x 0.92472 = 924.72 mL

molarity = 450/46.07 x 0.92472 = 10.563 M

c) For 0.25 mol ethanol

1000 ml solution contains = 10.563 x 0.92472 = 9.77 mol ethanol

so, 0.25 ml would be in = 250/9.77 = 25.60 ml

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