Chemistry · Solutions

Dilution and Molarity Explorer

Make a solution two ways. In dilution mode you take a volume of stock solution and add water up to a final volume. In dissolve mode you weigh a solid and fill a flask to the mark.

Watch the color, the concentration, and the moles of solute. Moles of solute stay the same when you add water, which is why M₁V₁ = M₂V₂. The Beer's law graph shows how color intensity tracks concentration.

Model notes

Molarity M = moles of solute ÷ liters of solution. Molar masses: CuSO₄ 159.61 g/mol (anhydrous), KMnO₄ 158.03 g/mol.
Volumes are treated as additive, and the final volume is the volume of the flask. Real solutions fill the flask to the mark after mixing, so the volume of water added is read off the flask, not assumed.
Solution color on screen is a model. Opacity rises with concentration up to a display maximum for each solute, so it is not a measurement of true color.
Beer's law: A = ε ℓ c, with path length ℓ = 1.00 cm. Approximate molar absorptivities: CuSO₄ about 12 M⁻¹cm⁻¹ at 810 nm, KMnO₄ about 2.4 × 10³ M⁻¹cm⁻¹ at 525 nm. Treat them as typical textbook magnitudes. Real values depend on wavelength and instrument. Absorbance is reported for a sample diluted 1:10 (CuSO₄) or 1:1000 (KMnO₄) so that readings fall near the useful range of 0.1 to 1.
Approximate solubility at 20 °C used for the warning: CuSO₄ about 1.3 M, KMnO₄ about 0.40 M. The slider limits keep you near those values.

Sources

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