Question

As solute is dissolved in a solvent, the vapor pressure of the solution changes according to Raoult's law

Psoln=Psolv×Xsolv

where Psoln is the vapor pressure of the solution, Psolv is the vapor pressure of the pure solvent, and Xsolv is the mole fraction of the solvent. If the solute dissociates into ions, the term Xsolv must be modified to take into consideration the total number of moles of particles in the solution, both ions and molecules. When a solution contains two volatile components, A and B, the total pressure of the solution is equal to the sum of the individual vapor pressures according to Dalton's law as follows:

Ptotal=PA×XA +PB×XB

Part A

At 55.0 ∘C, what is the vapor pressure of a solution prepared by dissolving 78.4 g of LiF in 265 g of water? The vapor pressure of water at 55.0 ∘C is 118 mmHg. Assume complete dissociation of the solute.

Part B

The solvent for an organic reaction is prepared by mixing 50.0 mLof acetone (C3H6O) with 75.0 mL of ethyl acetate (C4H8O2). This mixture is stored at 25.0 ∘C. The vapor pressure and the densities for the two pure components at 25.0 ∘C are given in the following table. What is the vapor pressure of the stored mixture?

Compound	Vapor pressure (mmHg)	Density (g/mL)
acetone	230.0	0.791
ethyl acetate	95.38	0.900

Psoln =

Answer 1

Please post Qn A as a new question