In chemistry, hydration energy (also hydration enthalpy) is the amount of energy released when one mole of ions undergoes solvation.

The hydration number of a compound is defined as the number of molecules of water bonded to a central ion, often a metal cation.

A hydration pack or drink bag is a type of hydration system built as a backpack or waistpack containing a reservoir or "bladder" commonly made of rubber or flexible plastic.

Water molecules bound in crystals.

a geochemical method of determining age in either absolute or relative terms of an artifact made of obsidian.

In chemistry, a hydration reaction is a chemical reaction in which a substance combines with water.