Dilution and concentration

Calculate stock volumes, distinguish 1 + n from 1 in n, and relate mass, final volume and molar mass.

Stock concentration, same units as targetWorking concentrationFinal volume (mL)Water parts in 1 + nMass of stated chemical form (g)Final volume for concentration (mL)Molar mass of that form (g/mol)

Calculate

Enter your values and calculate. Read the assumptions below before using a result.

Method and assumptions

Three calculations answer different questions. The first conserves the amount of dissolved material: C₁V₁ = C₂V₂. Put the two concentrations on the same basis before entering them. A percentage by mass cannot be substituted for a percentage by volume. The second interprets 1 + n as one part stock plus n parts water, so ten parts in total for 1 + 9. The third starts with a weighed mass of a named chemical form and a final solution volume.

With a 10% stock, a 1% target and 500 mL final volume, the stock aliquot is 50 mL. Make up to the final volume following the published procedure; the displayed 450 mL allowance is nominal and is not a guarantee that two liquid volumes add exactly. Separately, 10 g in a final litre is 10 g/L or 1% w/v. Molarity additionally requires the correct molar mass: choose the hydrate actually weighed, not its anhydrous relative.

The calculator deliberately does not determine solubility, heat release, mixing order, solution density, capacity or the suitability of a concentration for photographic use. A numerically valid answer can still describe an unsuitable solution. Copy the original formulation and its source into the notebook, then record the arithmetic and the amount actually measured. A target stronger than its stock is rejected because dilution cannot achieve it.

Try doubling the final volume while keeping both concentrations fixed. The stock requirement should double while the dilution factor stays the same. Explain why that is a conservation check rather than evidence that the preparation is safe.

Evidence and record

Read the teaching method and its sources. Keep your inputs, the displayed assumptions and the result together; a result detached from its conditions cannot be checked.