26H2O

26H2O is a chemical notation used to describe a hydrate in which twenty-six molecules of water are integrated into each formula unit of a compound. In formulas, hydrates are often written as X·nH2O, where X is the anhydrous compound and n is the number of water molecules. The specific water can be lattice water, which resides in the crystal lattice, or coordinated water, which is bound to a metal center in the inner coordination sphere. The presence of water molecules can influence physical properties such as solubility, density, stability, and color, and can play a structural role in crystal packing.

Determining the water content typically involves gravimetric analysis or thermogravimetric analysis, where the material is heated to remove water in steps and the mass loss is used to infer the hydration number. Infrared spectroscopy and X-ray crystallography can also help distinguish organized lattice water from coordinated water and reveal the arrangement of water molecules.

Note that 26H2O does not by itself define a unique chemical identity; it indicates a hydration state for a particular base compound. To identify the compound fully, the anhydrous core and the crystal structure must be specified. Hydrates with large n values are less common but occur in some inorganic salts and coordination compounds, especially under specific crystallization conditions or in porous materials.