dilution

Dilution is the process of reducing the concentration of a solute in a solution by adding more solvent or by removing some of the solution. It is commonly used to bring concentrations into a workable range for experiments, measurements, or reactions, and to prepare standards of known concentration.

The relationship between concentrations and volumes in dilution is described by the equation C1V1 = C2V2, where C1 and V1 are the concentration and volume of the solution taken for dilution, and C2 and V2 are the final concentration and final total volume after dilution. This means that C2 = (C1V1)/V2. If V2 equals V1 plus the added solvent, you can compute the required solvent volume to achieve a target concentration.

Common methods include dilution by volume and serial dilution. Dilution by volume adds solvent until the solution reaches a desired final volume, keeping the amount of solute constant. Serial dilution involves a sequence of successive dilutions, often using a constant dilution factor DF, achieved by transferring a fixed volume from one tube to the next and adding solvent each time. The dilution factor can be defined as DF = C1/C2 or DF = V2/V1, depending on the formulation.

Applications span chemistry, biology, medicine, and environmental science. Dilution is used to prepare assay standards, calibrate instruments, dilute samples for analysis, or adjust drug concentrations in pharmacology. Accuracy relies on precise volumetry, thorough mixing, and control of variables such as temperature and evaporation, all of which influence the final concentration.