Crystallization

Crystallization is a process by which a chemical compound or substance forms solid crystals precipitating from a solution, melt or more rarely deposited directly from a gas. Crystallization is a chemical reaction that occurs on a microscopic scale and results in the formation of a crystalline solid from a solution or melt.

Process

Crystallization occurs in two major steps. The first is nucleation, the appearance of a crystalline phase from either a supercooled liquid or a supersaturated solvent. The second step is known as crystal growth, which is the increase in the size of particles and leads to a crystal state. An important stage of this step is known as Ostwald ripening.

Types of Crystallization

There are different types of crystallization which include, but are not limited to:

• Evaporative Crystallization: This type of crystallization occurs when the solvent evaporates from a solution which contains a dissolved substance. As the solvent evaporates, the solution becomes more concentrated until the solute precipitates in the form of crystals.

• Cooling Crystallization: This type of crystallization occurs when a solution of a substance is cooled. As the solution cools, the solubility of the substance decreases, leading to the formation of crystals.

• Reactive Crystallization: This type of crystallization occurs when a chemical reaction produces a product that is insoluble in the reaction mixture, leading to the formation of crystals.

Applications

Crystallization has many practical applications. It is used in the chemical industry to separate and purify substances. It is also used in the pharmaceutical industry to produce pure active pharmaceutical ingredients (APIs). In the food industry, crystallization is used to produce table salt, sugar, and chocolate.

See Also

• Chemical compound
• Chemical reaction
• Nucleation
• Ostwald ripening
• Evaporative Crystallization
• Cooling Crystallization
• Reactive Crystallization

Crystallization Resources
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