In chemistry, concentration's the measure of how much of a given substance there's mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept's limited to homogeneous solutions, where it refers to the amount of solute in the solvent. To concentrate a solution, one must add more solute, or reduce the amount of solvent (for instance, by selective evaporation). By contrast, to dilute a solution, one must add more solvent, or reduce the amount of s… (More on Concentrations)