How to use this calculator
- Choose a known solute amount or a solute mass and formula.
- Enter the solvent mass and select its unit.
- Calculate and verify that the denominator is solvent mass in kilograms.
Formula and variables
m = n(solute) / mass(solvent in kg)
| Symbol | Meaning | Unit |
|---|---|---|
| m | molality | mol/kg |
| n | solute amount | mol |
Worked example
0.5 mol solute in 2 kg solvent has molality 0.25 mol/kg.
Interpretation
Molality uses solvent mass, not the final solution volume or total solution mass.
Common mistakes
- Use mass of solvent only.
- Do not confuse molality m with molarity M.
Frequently asked questions
What is the difference between molality and molarity?
Molality uses solvent mass. Molarity uses final solution volume.
Can I enter solute mass instead of moles?
Yes. Enter the solute formula so the calculator can derive its molar mass.
Does temperature change molality?
Temperature does not directly change molality because the denominator is mass, not volume.
Can I use scientific notation?
Yes. Enter values such as 6.022e23 or 1.0e-6 in a numeric field.
How should I round the result?
Keep extra digits during the calculation. Round the final result to the precision required by your data.