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Molarity and Solution Prep Calculator

How much solute to weigh out for a target concentration and volume.

Target concentration (mol/L)

Final volume (mL)

Molecular weight (g/mol)

Reagent purity (%)

How it works

Mass equals molarity times volume in litres times molecular weight. For a stock of known purity the result is divided by the purity fraction, because a 95 percent reagent needs proportionally more material.

Worth knowing

Dissolve in less than the final volume, then make up to the mark. Adding solvent to a full volume overshoots.
Molecular weight must match the hydrate you actually have: CuSO4 is 159.6, CuSO4·5H2O is 249.7.
For anything below about 10 mg, weigh a larger amount and dilute rather than trusting the balance.