Question

What are hydrated and unhydrated salts?

Answer 1

Hydrated salts: Word Hydrous is referred to a substance that contains water molecules as a constituent.

• These hydrous compounds are called hydrates.
• Here, water means the water of crystallization.
• These water can get trapped inside the crystal lattice of substances during crystallization.

Examples of hydrated salts

• $\mathrm{Copper}\left(\mathrm{II}\right)\mathrm{sulfate}\left({\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}\right)$
• $\mathrm{Ferrous}\left(\mathrm{II}\right)\mathrm{sulfate}\left({\mathrm{FeSO}}_4.7{\mathrm{H}}_2\mathrm{O}\right)$
• $\mathrm{Calcium}\mathrm{sulfate}\left({\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}\right)$

So, These are the examples of hydrated salts.

Anhydrous salts: Word anhydrous is referred to a substance that does not contain water as a constituent.

• It means the absence of water in a compound.
• These compounds are called anhydrous compounds or anhydrates.

Example of an anhydrate salt

• $\mathrm{Copper}\mathrm{sulfate}\left({\mathrm{CuSO}}_4\right)$

On strong heating, copper sulphate crystals lose all the water of crystallization and form anhydrous copper sulphate which is white in color.

Chemical Reaction

$$\begin{gathered} {\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}\stackrel{\mathrm{heat}}{\to }{\mathrm{CuSO}}_4 \\ \mathrm{Copper}\mathrm{sulfate}\mathrm{Copper}\mathrm{sulfate} \\ \left(\mathrm{Hydrated}\right)\left(\mathrm{Anhydrous}\right) \end{gathered}$$