CONCEPTS

What is crystallization?

We explain what crystallization is and what this chemical process consists of. In addition, the methods used and examples of crystallization.

  1. What is crystallization?

Crystallization is known as a chemical process in which a gas, a liquid or a solution is transformed  into a set of solid crystals . Said crystals consist of an ordered set of rigid molecular bonds, pure in their elementary nature, so that crystallization can be used to separate the ingredients from some homogeneous mixture.

Crystallization can be carried out by various methods, ranging from selective alteration of physical temperature or  pressure conditions , as well as the addition of certain chemical substances. The shape, size and quality of the crystals thus obtained will depend on the specific conditions in which the process occurs and the time during which it is allowed to occur.

The crystals obtained by this method are solid formations, endowed with a very well defined diffraction pattern. Depending on the element and the conditions in which crystallization occurs, they will have one way or another, and may have color, transparency and other chemical properties .

Crystals are common in the mineral nature  and are classified according to their properties in: solid crystals, luminous crystals, ionic
crystals, covalent crystals, molecular crystals and metallic crystals.

  1. Crystallization Examples

Crystallization
Water vapor from the air can crystallize directly on cold surfaces.
  • ormation of frost . Under certain conditions of ambient humidity , water vapor from the air can crystallize directly on cold surfaces such as glass or  metals , and form snow-like structures, called  frost . Some freezers tend to form it too. These are water crystals, whose constitution is very regular and very well formed.
  • Freezing  water . Ice is frozen water, and as such it is not a crystal. But during the early freezing phases of this liquid, you can see how dendrites and other submerged crystalline structures arise.
  • Evaporation  of  water  sea . To obtain salt crystals, as well as desalinated water, water taken from the sea is usually boiled. In this way, the liquid becomes a gas (water vapor) leaving the dissolved salts in the container. These, reuniting their molecules , take the form of perfect saline crystals.
  • Silver crystals for  photography . Silver crystals are useful for certain artifacts of the film industry or of old photography (not digital, obviously), since being sensitive to light, these crystals are rearranged against light, thus copying the light impression. To obtain them, compounds such as bromide, chloride or silver iodide are used.
  • Calcium oxalate crystals . Formed by the accumulation of salts and calcium in the kidneys, these crystals are usually painful and sometimes require even surgical intervention, as they hinder the normal expulsion of urine. They have the shape of small dark stones, known as kidney stones, or “stone” or “sand” in the kidneys.

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