The nature of a crystallization process is governed by both thermodynamic and kinetic factors, which can make it highly variable and difficult to control.
Despite the second principle of thermodynamics, crystallization usually occurs at lower temperatures (supercooling).
Crystallization is the (natural or artificial) process of formation of solid crystals from a homogeneous solution or melt, or more rarely directly from a gas.
Supersaturation is the driving force of the crystallization process—the rates of nucleation and growth are driven by supersaturation within the solution.
Once the solution is no longer supersaturated, the solid-liquid system reaches equilibrium and crystallization is complete, unless the operating conditions are modified from equilibrium so that the solution becomes supersaturated again.
Hence, molecular recognition is the principle of purification in crystallization.
The crystallization process consists of two major steps: nucleation and crystal growth.
The solution that remains after a crystallization process is called the mother liquor.
Crystallization is a valuable process for both research and industrial applications.