Tag: Water

HYDROUS AND ANHYDROUS

In IMDG Code we can see the terms hydrous and anhydrous. Hydrous means a chemical compound combined with water molecules and anhydrous means all water removed especially water of crystallization.

Photograph of a sample of anhydrous chromium(I...
Photograph of a sample of anhydrous chromium(III) chloride, CrCl 3 . Sample from Aldrich (99%, sublimed), CAS # 10025-73-7. Scene lit with natural sunlight. (Photo credit: Wikipedia)

Below are two examples of hydrous and anhydrous form of the same chemicals

Hydrated       =  UN 2672 AMMONIA SOLUTION Class 8)

Anhydrous     = UN 1005, AMMONIA, ANHYDROUS Class 2.3 / 8

Hydrated       = UN 1789 HYDROCHLORIC ACID Class 8

Anhydrous     = 1050 HYDROGEN CHLORIDE,   ANHYDROUS Class 2.3 / 8

Tin(II) oxide hydrate. It is pale yellow while...
Tin(II) oxide hydrate. It is pale yellow while the anhydrous form is blue-black (Photo credit: Wikipedia)

SODA LIME

Soda lime is generally used in anaesthesia and undersea breathing due its property of absorbing carbon dioxide. Soda lime is also used by navy in submarines, mining and petrochemical industries. The main ingredients of soda lime are Calcium hydroxide (about 75%), Water (about 20%), Sodium hydroxide (about 3%) & Potassium hydroxide (about 1%).

The hazard symbol for corrosive substances acc...

If soda lime is containing more than 4% sodium hydroxide then it is classified as Class 8, corrosive substances. UN number assigned to corrosive soda lime is UN 1907.