What is the mole fraction of a solute?

The mole fraction of a solute is the ratio of the number of moles of the solute to the total number of moles in the solution.

Formula:

Mole fraction of solute (Xₛ) = moles of solute / (moles of solute + moles of solvent)

Explanation:

• It is a unitless quantity
• Represents the proportion of solute in a solution
• Always lies between 0 and 1

Example:

If:

• Moles of solute = 2
• Moles of solvent = 8

Then:
Xₛ = 2 / (2 + 8) = 2 / 10 = 0.2

Key Insight:

• Mole fraction does not depend on temperature or pressure
• Useful in colligative properties and solution chemistry

Conclusion:

The mole fraction of a solute is a measure of its proportion in a solution, calculated as the ratio of its moles to total moles.