Crystallization.

form crystals, called crystals, from liquids (solutions or molten bodies) or gaseous states. Crystallization operations are often used to purification solids. The crystallization sequence is: (1
) dissolves the mixture to be purified in a suitable solvent of heat

; Soluble substances

3 ) allow the filter to cool slowly and crystallize, (4 ) filter out crystals,
drying
and test the purity of crystals. If the purity does not meet the requirements, then crystallize. In addition to purifying inorganic or
organic
, crystallization is also used to prepare special crystals, such as sodium chloride, sodium bromide and other crystals used on infrared
spectral
meters, crystalline palladium and crystalline silicon for semiconductors, and alumina crystals for laser technology. Solubility decreases with temperature and decreases a small number of substances, such as sodium chloride, potassium chloride, potassium carbonate, etc., can be concentrated with evaporative solvents to produce crystals. Substances whose solubility decreases significantly with the decrease of temperature, such as potassium nitrate, ammonium nitrate, sodium nitrate, etc., cool its saturated solution or a thick solution, so that the solution forms crystals from the solution. Generally the crystallization speed is slower, the crystal is bigger, the crystal is more complete.