Chemistry - Ideal Gas Question with Solution | TestHub
Two flasks X (3 L, kept at 300 K) and Y (6 L, kept at 400 K) are joined through a closed valve. X contains 0.0025 mol of liquid ethanol and Y contains 0.0100 mol of liquid ethanol (the volume of the liquid is negligible, and each flask has no other gas). The vapour pressure of ethanol is 40 mm Hg at 300 K and 200 mm Hg at 400 K. The valve is opened with the flasks kept at their temperatures. The final pressure in the flasks is ( = 62.4 L mm Hg/mol K)
Options:
Answer:
Solution:
Test the case that all 0.0125 mol is vapour at one pressure : = (_X/_X + _Y/_Y)/.
_X/_X + _Y/_Y = 3/300 + 6/400 = 0.010 + 0.015 = 0.025 L/K.
= /0.025 = 0.0125 x 62.4/0.025 = 31.2 mm Hg.
31.2 mm Hg is below the vapour pressure at both temperatures (40 mm at 300 K), so no liquid can remain: the assumption is consistent and = 31.2 mm Hg.
The values 40 and 200 mm Hg would apply only if liquid were left in X or Y.
Answer: ().
