How this calculation works
Use the final solution volume, not merely the volume of solvent added. Molarity is expressed as moles per litre and can vary with temperature as solution volume changes.
Molarity = moles of solute ÷ litres of final solutionA worked example
0.5 mol in a final solution volume of 2 L gives 0.25 mol/L.
Good to know
Assumes the idealized model described above. Use consistent units and independently verify figures before a consequential decision.
Final solution volume is not just the solvent poured in
Dissolving a solute and bringing the mixture to a specified final volume defines the denominator in molarity. Pouring a litre of solvent onto solute does not automatically produce exactly one litre of final solution.
That distinction separates a measured final solution from an assumed additive volume. The tool uses the final volume you enter and does not estimate how mixing changes it.
Moles and mass need a conversion before this step
The amount field expects moles, not grams. To use a weighed mass, first convert it using the appropriate molar mass and substance identity. Entering grams directly would answer a different question.
Molarity depends on solution volume, which can change with temperature. It is also different from molality, which uses mass of solvent as its denominator. Read the concentration definition before comparing results.
A few questions, answered
Does M mean mol/L?
In this context, molarity is expressed as moles of solute per litre of final solution.
Does the tool identify the solute’s molar mass?
No. You supply the amount in moles and the final solution volume.