Question #d75c8
1 Answer
The mole fraction of ethylene glycol is 0.414.
Explanation:
Raoult's Law states that the vapour pressure of a solvent in a solution is directly proportional to its mole fraction:
color(blue)(|bar(ul(color(white)(a/a) P_1 = χ_1P_1^°color(white)(a/a)|)))" "
where
P_1 is the vapour pressure of the solvent in the solutionχ_1 is the mole fraction of the solventP_1^° is the vapour pressure of the pure solvent
If the solvent is non-volatile, the formula can be arranged to
color(blue)(|bar(ul(color(white)(a/a)ΔP = χ_2P_1^°color(white)(a/a)|)))" "
where
ΔP" is the vapour pressure lowering of the pure solventχ_2 is the mole fraction of the solute.
The vapour pressure
Our task is to calculate the mole fraction of non-volatile solute (ethylene glycol) that will lower the vapour pressure of the solution to 1 atm at 110 °C.
