Mole Fraction Formula:
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Definition: Mole fraction of solvent is the ratio of the number of moles of solvent to the total number of moles of solute and solvent in a solution.
Purpose: It helps in understanding the composition of solutions and is particularly important in studying colligative properties like vapour pressure lowering.
The calculator uses the formula:
Where:
Explanation: The vapour pressure of the solvent in solution is divided by the vapour pressure of the pure solvent to determine the mole fraction of the solvent.
Details: Mole fraction is crucial for understanding solution behavior, predicting vapour pressure changes, and calculating other colligative properties like boiling point elevation and freezing point depression.
Tips: Enter the vapour pressure of the solvent in solution and the vapour pressure of the pure solvent. Both values must be > 0 and the solution pressure cannot exceed the pure solvent pressure.
Q1: What does the mole fraction represent?
A: It represents the proportion of solvent molecules in the entire solution, ranging from 0 to 1.
Q2: Why does vapour pressure decrease when solute is added?
A: Solute particles reduce the number of solvent molecules at the surface, lowering the escaping tendency (vapour pressure).
Q3: What's the range of possible mole fraction values?
A: Mole fraction always ranges between 0 (pure solute) and 1 (pure solvent).
Q4: How is this related to Raoult's Law?
A: This calculation is a direct application of Raoult's Law for ideal solutions.
Q5: Can I use different pressure units?
A: Yes, as long as both pressures are in the same units, the ratio (mole fraction) will be correct.