Lowering of vapor pressure is directly proportional to:
a) Temperature
b) Mole fraction of Solute
c) Mole fraction of Solvent
d) Amount of solution
can you please explain how?
delta Psoln = Xsolute*Posolvent
The lowering of vapor pressure is directly proportional to the mole fraction of the solute.
To understand why, let's break down the concept. Vapor pressure is the pressure exerted by the vapor in equilibrium with its liquid phase at a given temperature. When a non-volatile solute is dissolved in a solvent, the vapor pressure of the solvent decreases. This effect is known as the lowering of vapor pressure.
The Raoult's law provides a mathematical relationship between the vapor pressure of the solvent in a solution and its mole fraction. According to Raoult's law, the vapor pressure of the solvent in the solution is equal to the product of the mole fraction of the solvent and its vapor pressure in the pure state.
Mathematically, we can express this relationship as:
P_solvent = X_solvent * P_solvent^0
Where:
P_solvent is the vapor pressure of the solvent in the solution,
X_solvent is the mole fraction of the solvent, and
P_solvent^0 is the vapor pressure of the pure solvent.
From this equation, it is evident that as the mole fraction of the solute increases, the mole fraction of the solvent decreases, resulting in a decrease in the vapor pressure of the solvent.
Therefore, the correct answer is b) Mole fraction of Solute.