What is the equilibrium partial pressure of water vapor over mixture of water and ethanol?
October 13th, 2008
Chemistry Tutor Site - Problem
What is the equilibrium partial pressure of water vapor above a mixture of 24.0 g H2O and 48.0 g CH3CH2OH at 25 °C. The partial pressure of pure water at 25.0 °C is 23.8 mm Hg. Assume ideal behavior for the solution.
Chemistry Tutor Site - Answer
24.0 g / 18.02 g/mol = 1.33 moles water
48.0 g / 46 g/mol= 1.04 moles CH3CH2OH
total moles = 1.33 + 1.04 = 2.37
Moles fraction water = 1.33 / 2.37 = 0.561
p = p°(water ) X (water) => Raoult’s law
p = 23.8 x 0.561 = 13.4 mm Hg
Entry Filed under: Equilibrium Chemistry
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