Answer:
Vapor pressure of solution → 151.1 Torr
Option 2.
Explanation:
Raoult's Law is relationed to colligative property about vapor pressure. A determined solute, can make, the vapor pressure of solution decreases.
ΔP = P° . Xm
where Xm is the mole fraction of solute, P° (vapor pressure of pure solvent)
and ΔP = Vapor pressure of pure solvent - Vapor pressure of solution.
In order to determine the vapor pressure of solution, we need to determine, the vapor pressure of B and A in the solution
B's pressure = P° B . Xm
When we add A to B, A works as the solute and B, as the solvent.
Vapor pressure of pure B is 135 torr. (P° B)
In order to determine, the Xm, we use the moles of A and B
Xm = 5.3 mol of B / (1.28 + 5.3) → 0.806
B's pressure = 135 Torr . 0.806 → 108.81 Torr
If mole fraction of B is 0.806, mole fraction for A (solute) will be (1 - 0.806)
A's pressure = 218 Torr . 0.194 → 42.3 Torr
Vapor pressure of solution is sum of vapor pressures of solute + solvent.
Vapor pressure of solution = 42.3 Torr + 108.81 Torr → 151.1 Torr
