Question #e2d82

1 Answer
May 25, 2017

An anhydrate, or an anhydrous salt


A hydrate is formed when water becomes "trapped" in the crystalline structure of a solid, and the surrounding water is evaporated.

There is a whole-number ratio of the number of water molecules per salt unit, such as #"FeCl"_3 * 6"H"_2"O"# [iron(III) chloride hexahydrate] and #"CuSO"_4 * 5"H"_2"O"# [copper(II) sulfate pentahydrate].

The water associated with these hydrates is called water of hydration, or the water of crystallization, and after this water is removed, the remaining substance is the anhydrous salt, or simply the anhydrate.