Calculate molality from moles of solute and mass of solvent, and compare with molarity.
Molality uses solvent mass rather than solution volume, so it is independent of temperature. That is why colligative property equations — boiling point elevation, freezing point depression — are written in molality. For dilute aqueous solutions molality and molarity are nearly equal, but they diverge markedly at high concentration or in dense solvents.
Molality
b = moles of solute ÷ kilograms of solvent
b = moles of solute ÷ kilograms of solvent Molality uses solvent mass rather than solution volume, so it is independent of temperature. That is why colligative property equations — boiling point elevation, freezing point depression — are written in molality.
For dilute aqueous solutions molality and molarity are nearly equal, but they diverge markedly at high concentration or in dense solvents.
This calculator takes 4 inputs: Moles of solute, Mass of solvent, Solution density, Molar mass of the solute. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.