If a solution has a vapor pressure of 80 mmHg and the pure solvent has a vapor p

If a solution has a vapor pressure of 80 mmHg and the pure solvent has a vapor pressure of 100 mmHg, what is the mole fraction of the solvent?

If a solution has a vapor pressure of 80 mmHg and the pure solvent has a vapor pressure of 100 mmHg, what is the mole fraction of the solvent?

Correct Answer: 0.8

Step 1: Understand that vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid at a given temperature.
Step 2: Identify the vapor pressure of the solution, which is given as 80 mmHg.
Step 3: Identify the vapor pressure of the pure solvent, which is given as 100 mmHg.
Step 4: Use Raoult's Law, which states that the vapor pressure of a solution is equal to the mole fraction of the solvent times the vapor pressure of the pure solvent.
Step 5: Set up the equation: Vapor pressure of solution = (Mole fraction of solvent) x (Vapor pressure of pure solvent).
Step 6: Substitute the known values into the equation: 80 mmHg = (Mole fraction of solvent) x 100 mmHg.
Step 7: Solve for the mole fraction of the solvent by dividing both sides by 100 mmHg: Mole fraction of solvent = 80 mmHg / 100 mmHg.
Step 8: Calculate the mole fraction: Mole fraction of solvent = 0.8.
Step 9: Since the mole fraction of the solvent is 0.8, the mole fraction of the solute can be found by subtracting from 1: Mole fraction of solute = 1 - 0.8 = 0.2.
Step 10: Verify that the mole fraction of the solvent is indeed 0.8, which corresponds to the correct calculation.

Raoult's Law – Raoult's Law states that the vapor pressure of a solvent in a solution is equal to the vapor pressure of the pure solvent multiplied by the mole fraction of the solvent in the solution.
Mole Fraction Calculation – The mole fraction is calculated as the ratio of the number of moles of the component to the total number of moles in the solution.