Hydrates


 * Hydrates**

Hydrates are compounds formed by the addition of water to a host molecule. Hydrates are used in construction, refractories, and cement products. Since dissolving is an endothermic process, heat is being absorbed in the formation of hydrates.

A salt with associated water of crystallization is known as a hydrate. The structure of hydrates can be quite elaborate, because of the existence of hydrogen bonds that defines these ionic structures. Historically, the structures of many hydrates were unknown, and the dot in the formula of a hydrate was employed to specify the composition without indicating how the water is bound. Hydrated ionic compounds are those ionic compounds which contain water molecules inside their crystal lattice. The water is not chemically bonded to the crystal in any way, and may be driven off by heating the hydrated compound.

Examples: CuSO4•5H2O - copper (II) sulphate pentahydrate CoI2•6H2O - cobalt (II) iodide hexahydrate SnCl2•2H2O - stannous (tin II) chloride dihydrate

__Methane Hydrates__ Methane hydrates, or otherwise known as methane clathrates, are a solid form of water that contain a large amount of methane within its crystal structure. Methane hydrates are evaluated as potential fuel for the future. Many believe there is enough to supply energy for hundreds, maybe thousands, of years. Gas hydrates are formed by bringing the gas into contact with liquid water in high pressure and low temperature. This allows the escaping of gas. They are found in sea floor sediments and in the Arctic.

Sources: http://en.wikipedia.org/wiki/Hydrate http://en.wikipedia.org/wiki/Image:Cobalt%28II%29_chloride.jpg http://en.wikipedia.org/wiki/Image:Cobalt%28II%29-chloride-hexahydrate-sample.jpg http://en.wikipedia.org/wiki/Water_of_crystallization http://en.wikipedia.org/wiki/Methane_clathrate