What is crystallization?


In the field of chemistry there are a large number of important chemical processes which are chemical or physical operations that have the ability to transform the initial substances into products that turn out to be completely different. One of these chemical processes is known as crystallization, a process or technique through which solid compounds can be purified.

Crystallization What is it, what is it for, applications, process, examples 

What is crystallization?

The crystallization is a process by which one can make the dissolution of a solid considered impure in the least amount possible to obtain through the use of the solvent correct and high temperatures to achieve obtain a solution saturated when it cools produces crystallization.

  • What does it consist of
  • What is crystallization for?
  • Process
  • Applications of crystallization
  • Experiment
  • Examples of crystallization

What does it consist of

Crystallization is a chemical process that consists of the transformation of a gas , a liquid or some type of solution , into a group of crystals that have a solid consistency, a simpler definition would be a chemical process of solidification from a gas. It is a technique that is based on the separation of solutions when conditions can be adjusted in such a way that only one of the solutes can crystallize, while the other remains in solution.

What is crystallization for?

Crystallization is a process that has the ability to separate the solid components to form a homogeneous mixture and for this reason it serves as a purification method . By means of crystallization, it is then possible to obtain products having a purity percentage of up to 99%. It also helps you create uniform crystals that are easier to pack, handle and store. It notably improves the product to be crystallized for better commercialization .


It is important to mention that in the crystallization process the crystals have to be formed first in order to grow later. This formation process is known as nucleation and, when the crystal layer begins to form, it is called growth. They are two important stages that occur during the crystallization process.

  • Nucleation : this stage occurs during the formation of the first ions from the molecules that are located within the solution. Nucleation can occur as primary or secondary. The primary occurs when the origin of the new solid phase is not conditioned nor has it had an influence due to the presence of the solid phase that occurs.

On the other hand, secondary nucleation is responsible for designating the crystal formation process in the new phase, which will be conditioned by the presence of particles that belong to the same phase within the system that is supersaturated.

  • Growth : in this stage, the atoms that make up the liquid join the solid in order to form larger crystalline structures.

Applications of crystallization

With several applications in which crystallization can be used, among them we mention:

  • Crystallization of sucrose in the field of the sugar industry.
  • In the medical field to obtain drugs such as aspirin .
  • In the separation of waxes during the refining process of oils.
  • Purification of products derived from petroleum.


An example of an experiment can be carried out on sugar crystals . To do this, you will need a piece of string, 3 cups of white sugar, 1 cup of boiling water, a glass jar, a small stick, and food coloring.

First, the jar must be filled with the previously boiled water and the vegetable coloring is added to it, later, the sugar will be added little by little until it dissolves completely. The rope must be tied to the pencil and the sugar is gently rubbed on the rope, and then the stick is placed in the mouth of the jar, so that the rope can hang in the water that is sugary.

It is important to prevent the cord from touching the bottom of the jar. The jar is then placed in a warm place and left in place for at least a week. After this time has elapsed, it will be possible to observe the sugar crystals forming on the rope.

Examples of crystallization

Some examples of crystallization are as follows:

  • Frost formation: it occurs under some conditions of humidity in the environment that cause the water vapor that is present in the water to crystallize directly on cold surfaces, thus forming snow-like structures.
  • Freezing of water : during the first phases of freezing of water, a series of crystals appear in the liquid.
  • Evaporation of sea water : when sea ​​water evaporates at the time it is boiled, salt crystals are obtained which are observed as a type of crystal.
  • Calcium oxalate crystals : these are formed by the accumulation of salts and calcium in the kidneys, which are painful for humans.

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