Saturation

In physical chemistry, saturation is the point at which a solution of a substance can dissolve no more of that substance. This point, the saturation point, depends on the temperature of the liquid as well as the chemical nature of the substances involved. This can be used in the process of recrystallisation to purify a chemical: it is dissolved to the point of saturation in hot solvent, then as the solvent cools and the solubility decreases, excess solute precipitates[?]. Impurities, being present in much lower concentration, do not saturate the solvent and so remain dissolved in the liquid.

In organic chemistry, saturation refers to an organic compound having the maximum amount of hydrogens possible: i.e., no double bonds. Of simple hydrocarbons, alkanes are saturated, and alkenes are unsaturated. The term is applied similarly to the fatty acid constituents of lipids, where the fat is described as saturated or unsaturated, depending on whether the constituent fatty acids contain carbon-carbon double bonds.

Similarly, an atmospheric humidity of 100% represents the saturation point, at which the air can hold no more moisture.

- see also Dew point

For magnetic materials, saturation is the state when the material cannot absorb a stronger magnetic field, such that an increase in magnetization[?] does not produce significant change in magnetic flux density.

1. In a communications system, the condition at which a component of the system has reached its maximum traffic-handling capacity.

Note: Saturation is equivalent to one erlang per circuit.

2. The point at which the output of a linear device[?], such as a linear amplifier, deviates significantly from being a linear function of the input when the input signal is increased.

Note: Modulation often requires that amplifiers operate below saturation.

Source: from Federal Standard 1037C and from MIL-STD-188