Solutions & Dilutions

Concentration, molarity, and the dilution equation

When a solution is diluted by adding solvent, the amount of solute (in moles) remains constant. Only the volume changes, which decreases the concentration proportionally. The dilution equation C₁V₁ = C₂V₂ expresses this conservation: C₁ is the initial molarity, V₁ is the initial volume, C₂ is the final molarity, and V₂ is the final volume (V₁ + added water). Serial dilution is a technique where each step dilutes the previous solution by a fixed ratio, useful for preparing very low concentrations. Color intensity of many solutions is proportional to concentration (Beer-Lambert Law), providing a visual indicator of dilution progress.