Frequently Asked Questions

Molarity (mol/L) is moles of solute per liter of solution; molality (mol/kg) is moles of solute per kilogram of solvent only. Molality doesn't change with temperature since it's mass-based, while molarity does since volume expands with heat.

Molarity is based on solution volume, but mass percent and molality are mass-based. Density is what links mass to volume, so it's required to convert between them.

Mass percent is the mass of solute divided by the total mass of the solution, times 100 — for example, a 10% w/w salt solution has 10 g of salt per 100 g of total solution.

Parts per million (ppm) is mass percent multiplied by 10,000 — it's just a more convenient scale for very dilute solutions, where percent values would be tiny fractions.

Molarity and molality are both defined in moles, while mass percent and ppm are mass-based. Molar mass is the conversion factor between mass and moles for a given substance.

No, this calculator is designed for liquid solutions using mass and volume-based units. Gas concentrations typically use mole fraction or partial pressure instead.

That signals your inputs are inconsistent — for example, a molarity too high for the given density and molar mass to be physically possible. Double-check your values.

Density (and therefore molarity) is temperature-dependent, so results are only as accurate as the density value you enter for that specific temperature. Molality and mass percent aren't affected by temperature.

Molarity is most common for everyday lab solution prep since it's volume-based and easy to measure with a volumetric flask. Molality is preferred when temperature will change, such as in colligative property calculations.

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