Question

Why does crystallization separate mixtures?

Answer 1

The majority of minerals and organic molecules crystallise readily, and the resultant crystals are typically of excellent quality, that is, free of apparent flaws. Larger biological particles, such as proteins, are, on the other hand, notoriously difficult to crystallise. The intensity of either atomic forces (in the case of mineral substances), intermolecular forces (organic and biochemical substances), or intramolecular forces (in the case of organic and biochemical substances) greatly influences the ease with which molecules condense (biochemical substances).

Complete answer:
The process of crystallisation is used to purify substances. A method for extracting solids from a solution. Crystallization is the process through which a substance's atoms/molecules organise themselves in a well-defined three-dimensional lattice, reducing the system's total energy. When a material crystallises, its atoms or molecules form well-defined angles that link them together.
When a solid material is mixed with a liquid and stirred, the solid dissolves in the liquid. However, as additional solid is added to the liquid, a point is reached where no more solid can dissolve. This is referred to as a saturation point, and the fluid is referred to as a saturation solution.
The gradual precipitation of crystals from a saturated solution is known as crystallisation.
The technique is known as fractional crystallisation or recrystallization when it is employed to cleanse an impure material. You use a suitable solvent to heat a sample of the impure chemical to its boiling point. Then you add just enough additional solvent to dissolve the substance completely. The solution is saturated at this stage. The solubility of the chemical diminishes as the solution cools. The pure compound precipitates as crystals. In the solution, the impurity, which is present in tiny amounts, stays unsaturated. Crystals of the pure chemical remain on the filter paper after filtering the cool mixture.

Note:
Salt crystallisation is the most practical use of crystallisation today, as well as the most cost-effective method of producing salt. The technique can also be used for compound purification and crystal production. Water of crystallisation may also be described as the water molecules that make up the structure of a crystal. The crystals are formed and crystallised by them. Copper sulphate ( $CuS{{O}_{4}}.\text{ }5{{H}_{2}}O$ ) is an antibacterial and antifungal agent that may be used topically.