During dilution, the concentration of a solution decreases. This occurs because dilution involves adding a solvent—usually water—to a solution, which increases the total volume of the solution while the amount of solute (the substance dissolved in the solvent) remains constant.
When the volume of solvent increases, the ratio of solute to the total volume of solution decreases, resulting in a lower concentration. Concentration is defined as the amount of solute per unit volume of solution. Therefore, as the volume increases due to the addition of more solvent, and the amount of solute does not increase, the concentration diminishes.
This principle is fundamental in chemistry and is often expressed through the dilution equation, C1V1 = C2V2, where C represents concentration and V represents volume. In this formula, the initial concentration multiplied by the initial volume equals the final concentration multiplied by the final volume. When adding solvent and thus increasing the final volume, the final concentration must correspondingly decrease if the amount of solute remains unchanged.