Editing Concentration (section)

==Qualitative description==

[[Image:Dilution-concentration simple example.jpg|frame|right|These glasses containing red dye demonstrate qualitative changes in concentration. The solutions on the left are more dilute, compared to the more concentrated solutions on the right.]]

Often in informal, non-technical language, concentration is described in a [[qualitative data|qualitative]] way, through the use of adjectives such as "dilute" for solutions of relatively low concentration and "concentrated" for solutions of relatively high concentration. To '''concentrate''' a solution, one must add more [[solute]] (for example, alcohol), or reduce the amount of [[solvent]] (for example, water). By contrast, to '''dilute''' a solution, one must add more solvent, or reduce the amount of solute. Unless two substances are [[miscible]], there exists a concentration at which no further solute will dissolve in a solution. At this point, the solution is said to be [[Saturated solution|saturated]]. If additional solute is added to a saturated solution, it will not dissolve, except in certain circumstances, when [[supersaturation]] may occur. Instead, [[Phase (matter)#Phase separation|phase separation]] will occur, leading to coexisting phases, either completely separated or mixed as a [[suspension (chemistry)|suspension]]. The point of saturation depends on many variables, such as ambient temperature and the precise chemical nature of the solvent and solute.

Concentrations are often called '''levels''', reflecting the mental [[schema (psychology)|schema]] of [[ordinate|levels on the vertical axis]] of a [[chart|graph]], which can be [[height|high or low]] (for example, "high serum levels of bilirubin" are concentrations of [[bilirubin]] in the [[serum (blood)|blood serum]] that are greater [[Reference ranges for blood tests#Bilirubin reference ranges|than normal]]).