Help Chem. Thanks. Ethanol is commonly referred to simply as alcohol or spirits.

Question

Help Chem. Thanks.

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 CH_3CH_2OH. 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 (C_2H_5OH) and 1-propanol (C_3H_7OH) at 35 degree C are 100.0 mmHg and 37.6 mmHg, respectively. Assume ideal behaviour and calculate the partial pressures of ethanol and 1-propanol at 35 degree C over a solution of ethanol in 1-propanol, in which the mole fraction of ethanol is 0.200.

Explanation / Answer

a) Moles of this 45% solution is

45 gms of this solution is Ethanol

so moles of ethanol = 45/46.06 = 0.97 moles

Now determine volume of 100.0 g of solution by the formula density = mass/volume

0.92 = 100/volume

volume = 100/. 92 = 108 ml

so now molarity = moles * 1000/ volume in ml

M= 0.97 *1000/108

= 970/108 = 8.9 M

8.9 M is the molarity of the solution.

c) The molarity of the solution is 8.9 M

M= moles *1000/ volume in ml

8.9 = 0.25 *1000/ volume in ml

the volume that has .25 moles of ethanol (ml) = 250/8.9

= 28 ml

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