Molarity Tool
Determine molar concentration from solute mass or amount and solution volume. Find required solute mass or solution volume, solve stock dilution relationships, and estimate mixture concentration using clear results, supporting calculations and concentration comparison charts.
Find molarity from solute mass, molar mass and solution volume.
Table of Contents
Highlights
- Calculate molarity from solute mass or amount.
- Determine required solute mass or solution volume.
- Solve for any unknown simple dilution variable.
- Estimate final molarity when combining two solutions.
- View concentration charts and export results as CSV, JSON or SVG.
How Molarity Tool Works?
Molarity measures the amount of dissolved solute per volume of the final solution. Enter solute amount directly, or provide solute mass and molar mass to determine the amount first.
Here, C is molarity (mol/L), n is solute amount (mol), V is final solution volume (L), m is solute mass (g), and MM is molar mass (g/mol). Rearranging the relationship gives the solute mass needed to prepare a target concentration or the final volume needed for a specified amount.
For dilution of a single stock solution, the amount of solute is conserved. Any one of the four variables can be determined from the other three. The diluent volume to add is the final volume minus the stock volume.
When combining two solutions containing the same solute, their solute amounts are added and divided by their combined volume.
| Calculation | Key inputs | Main output |
|---|---|---|
| Molarity | Solute mass and molar mass, or amount; final volume | Concentration (M) |
| Required mass | Target concentration, volume, molar mass | Mass (g) |
| Required volume | Solute amount or mass, target concentration | Volume (L) |
| Dilution | Three of C₁, V₁, C₂, V₂ | Missing dilution variable and diluent volume |
| Mixing | Two concentrations and two volumes | Final concentration (M) |
The results also show intermediate solute amounts, relevant volume or concentration values, and a comparative concentration chart where applicable.
Practical Use Cases
Students: Work through preparation exercises using a known solute mass, molar mass and final flask volume, then check the resulting molarity against the expected answer.
Laboratory technicians: Find the mass of a reagent needed to prepare a specified volume of solution at a target concentration.
Research scientists: Determine stock volumes and diluent additions for working solutions, or solve for an unknown stock concentration from a dilution relationship.
Biochemistry researchers: Estimate the final concentration after combining two aliquots containing the same dissolved compound.
Chemistry educators: Compare stock, diluted and mixed concentrations visually while explaining conservation of solute amount.
Accuracy and Limitations
Results follow the entered numbers and are displayed with roughly six significant digits; the underlying calculations use JavaScript floating-point arithmetic. Dilution assumes solute is conserved, while mixing assumes the two solutions contain the same solute and that their volumes are additive. The calculations do not account for chemical reactions, precipitation, evaporation, temperature-driven volume changes or experimental measurement uncertainty. Dilution inputs must also describe a genuine dilution, not a concentration increase.
