Enter the molality, mole fraction, and molar mass of the solvent into the calculator to determine the missing variable.

Mole Fraction To Molality Calculator

Mole Fraction ↔ Molality
Molality ↔ Molarity
Mass % ↔ Molality

Enter any 2 values to calculate the missing variable


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Mole Fraction to Molality Formula

The following formula is used to calculate the molality from the mole fraction and molar mass of the solvent.

m = \frac{X \cdot (1000 / M)}{1 - X}

Variables:

  • m is the molality (mol/kg)
  • X is the mole fraction
  • M is the molar mass of the solvent (g/mol)

To calculate the molality, multiply the mole fraction by 1000 divided by the molar mass of the solvent, then divide by 1 minus the mole fraction.

Mole Fraction to Molality Conversion Table (Solvent: Water, M = 18.015 g/mol)
Mole Fraction (solute) Molality (mol/kg)
0.0010.056
0.0020.111
0.0050.279
0.010.561
0.0150.845
0.021.133
0.031.717
0.042.313
0.052.922
0.063.543
0.084.827
0.106.168
0.159.790
0.2013.878
0.2518.503
0.3023.790
0.3529.121
0.4037.007
0.4545.417
0.5055.510
Assumes water as solvent (M = 18.015 g/mol). Formula used: b = [X × (1000/M)] ÷ (1 − X), where X is solute mole fraction.

What is Mole Fraction to Molality?

Mole fraction to molality is a conversion process used in chemistry to express the concentration of a solute in a solution. Mole fraction is the ratio of the number of moles of a component to the total number of moles in the mixture, while molality is the number of moles of solute per kilogram of solvent. This conversion is important in various chemical calculations and processes, as it allows for the determination of the concentration of a solution in different units, which can be more convenient for certain applications.

How to Calculate Mole Fraction to Molality?

The following steps outline how to calculate the Mole Fraction to Molality.


  1. First, determine the mole fraction (X) of the solute in the solution.
  2. Next, determine the molar mass (M) of the solvent in grams per mole.
  3. Next, use the formula m = (X * (1000 / M)) / (1 - X) to calculate the molality (m).
  4. Finally, calculate the molality using the values obtained.
  5. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Mole fraction (X) = 0.2

Molar mass of solvent (M) = 18 g/mol