Hydrated Salts
A hydrated salt is a crystalline salt molecule that is loosely connected to a small number of water molecules. When the anion of an acid and the cation of a base are joined to form an acid-base molecule, salt is formed. An anhydrate is a salt molecule that is not bound to any water molecules, while a hydrated salt is one that is bound to water molecules.
The water molecules in a hydrated salt are incorporated into the crystalline structure of the salt. A hydrated salt is one in which the ions in its crystalline structure are coupled with a number of water molecules. These water molecules are referred to as crystallisation fluids or hydration waters. Hydrated salts are salts that contain water during crystallisation. Every hydrated salt has a fixed number of crystallisation water molecules in its single ‘formula unit.’
The following are some examples of hydrated salts.
- CuSO4.5H2O copper sulphate crystals, which include 5 molecules of crystallisation water in one formula unit. Copper sulphate pentahydrate is the chemical name for it.
- Calcium sulphate crystals, often known as gypsum crystals, are written as CaSO4.2H2O because they contain two molecules of water of crystallisation in one formula unit. Calcium sulphate dihydrate is another name for it.
- Sodium carbonate crystals, also known as washing soda crystals, are written as Na2CO3.10H2O because each formula unit contains 10 molecules of water of crystallisation. It’s known as sodium carbonate decahydrate
Copper sulphate, Calcium sulphate, and Sodium carbonate are some of the hydrated salts based on the above-mentioned examples. Hydrated salts can be found in a variety of conditions, including freshwater. Salt has a flexible crystalline structure that allows it to easily bond to water molecules and becomes hydrated. Sodium chloride or salt absorbs water vapour in the air or comes into touch with liquid water. Free-flowing chemicals, for example, generate salt molecules when the compounds in a particular area’s soil or rock dissolve and mix with the groundwater, eventually becoming hydrated with the water molecules.
Water of Crystallization
Crystallization is a technique for separating solids from a solution or, to put it another way, a procedure for purifying things. This is the most frequent method for purifying seawater. Some salts have a few water molecules in their crystal structure as an essential component. The water of crystallisation refers to the water molecules that make up a crystal’s structure. Hydrated salts are salts that contain the water that causes crystallization. Below is a detailed explanation of crystallisation of water, hydrated and anhydrous salts, and also the action of heat on the hydrated salts.