Übersättigung

Übersättigung is a German term that translates to supersaturation in English. It describes a state where a solution contains more solute than it can dissolve at a given temperature and pressure. This state is unstable and can be disturbed by various factors, leading to the precipitation of the excess solute.

Supersaturation occurs when a saturated solution is cooled or when the solvent evaporates. For instance, if a saturated sugar solution is carefully cooled without any disturbance, it can remain supersaturated. The excess sugar is still dissolved, but it is not in equilibrium with the solid sugar.

The excess solute in a supersaturated solution is highly prone to crystallization. Even a small disturbance, such as introducing a seed crystal, scratching the container, or agitating the solution, can trigger rapid crystallization. This process releases the excess solute from the solution, forming solid crystals.

This phenomenon has practical applications. For example, it is utilized in the formation of rock candy, where a supersaturated sugar solution is allowed to crystallize over time. It also plays a role in geological processes, such as the formation of mineral deposits. In chemistry, understanding supersaturation is crucial for controlling crystallization processes in synthesis and purification. The degree of supersaturation influences the rate of nucleation and crystal growth, affecting the size and morphology of the resulting crystals.