Mole Fraction Calculator
Calculate the mole fraction of a solution by entering the amount of solute and solvent below.
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How to Calculate the Mole Fraction of a Solution
The mole fraction is the ratio of one substance in a solution to the moles of all substances in a solution, and it’s commonly used in chemistry. So, in order to find the mole fraction of a substance in a solution, you will need to know the amount of the substance (solute) and the amount of the remaining substance (solvent).
Since a mole fraction is a ratio, you can find it by dividing the amount of one substance in a solution by the total amount of solution.
Mole Fraction Formula
So, to solve the mole fraction, you can use the following formula:
XA = A (mol) / A (mol) + B (mol)
Thus, the mole fraction XA of a substance A in a solution of A and B is equal to the amount of solute A in moles divided by the sum of the amount of solute A in moles and the amount of solvent B in moles.
A simpler representation of this formula might look like this:
mole fraction = solute (mol) / solute (mol) + solvent (mol)
For example, let’s calculate the mole fraction of solute A in a solution composed of 2 moles of solute A and 4 moles of solvent B.
XA = 2 / 2 + 4 = 2 / 6 = 1 / 3
The mole fraction XA in this example is equal to 1/3, or 0.33.
We can also find the mole fraction of B in this substance.
XB = 4 / 2 + 4 = 4 / 6 = 2 / 3
The mole fraction XB in this example is equal to 2/3, or 0.67.
It’s important to note that since the mole fraction is a ratio of one compound in a substance to the whole, the mole fractions of each compound in the substance should sum to 1.
- LibreTexts, Mole Fraction, 2021, July 2, https://chem.libretexts.org/@go/page/53833