Ethanol evaporation? Nobody can figure this out! 10 points to first who gets it right!?

Question

You are given 1L of ethanol.

If you place this 1L ethanol in a 3m x 2.5m x 2.5m room, not all of the ethanol will evaporate.

The Question, then, is:
How much will remain if the vapor pressure of ethanol at 25C is 59mm Hg and the density of the liquis at 25C is .785 g/cm^3?

when calculated, the area of the room is 18.75 m^3

Answer 1

Calculate the volume of the room. Using the ideal gas equation (PV=nRT) and the partial pressure of 59 mm Hg at 25°C, find the mass of ethanol in the room. Subtract this mass from the mass of 1 liter of ethanol and you have your answer. You may have to convert between grams of ethanol and cm^3 of ethanol depending on what units the question needs to be answered.

Answer 2

Use the ideal gas law.

PV=nRT

n=PV/RT

Convert torr (mm Hg) to Pascals
(59mm Hg) (7.5×10^−3 Pa / mm Hg) = 0.44Pa

Express temp in Kelvins
25C = 298K

V = 3m x 2.5m x 2.5m = 18.75m^3

n = (0.44Pa) (18.75m^3) / [(8.3143 m^3·Pa·K^-1·mol^-1)(298K)]
n = 3.33x10^-3 mol

Convert moles to grams

(3.33x10^-3 mol)(46 g/mol) = 0.153g

then convert grams to liters

(0.153g) / [(0.785 g/cm^3) (10^3 cm^3/L)] = 1.945 x10^-4 L

So roughly 196μL evaporates.

Answer 3

I won't let any ethanol evaporate, I'll just dilute with water it to 40% and have a party.