Table of Contents
Algebraic definitions of solution concentration. The examples are numerical models, not instructions for preparing, diluting or mixing household products or medicines. Equations use a decimal point.
1Amount concentration
Amount concentration c is amount of solute n divided by final solution volume V. The SI unit is mol/m³; mol/L is also commonly used. M_m denotes molar mass in g/mol. The symbol M_m is not the concentration symbol. [1] c = n / V; n = m / M_m. 1 mol/L = 1000 mol/m³.
2Mass per volume and mass fraction
A stated 5 g per 100 mL of final solution is a mass concentration of 50 g/L. No solution density is needed to divide that value by molar mass. A mass fraction w = 0.05 instead needs solution density ρ to reach a volume basis. The following comparison assumes M_m = 100 g/mol and, for the mass-fraction case only, ρ = 1200 g/L. These are hypothetical values, not product specifications. [1] c = 50 / 100 = 0.5 mol/L. c = wρ / M_m = 0.05 × 1200 / 100 = 0.6 mol/L.
3Mass example
Using an assumed NaCl molar mass M_m = 58.44 g/mol, the mass corresponding algebraically to c = 0.1 mol/L and V = 0.25 L is shown below. V is final solution volume, not solvent volume. This does not establish a preparation procedure. [1] m = c M_m V = 0.1 × 58.44 × 0.25 = 1.461 g.
4Dilution as an identity
For the same solute, with its amount conserved and no reaction or loss, c1V1 = c2V2. In this identity, V2 is final solution volume; it does not mean that V2 of solvent is added. [1] V1 = c2 V2 / c1 = 0.1 × 0.25 / 1.0 = 0.025 L = 25 mL.
Results depend on the stated assumptions. Sources checked on 2026-10-03.
