Barium iodide is an inorganic compound that is made up of barium and iodine. By definition, an iodide is any compound that consists of iodine having one negative charge due to the acceptance of an electron for achieving the octet valence electronic configuration. Hence, Barium Iodide is an ionic compound that consists of a barium atom donating one electron and iodine accepting one electron to form a metal halide. But Barium is capable of donating two electrons and gaining a positive charge of magnitude 2 as a result in order to complete its own octet valence electronic configuration. Hence, one barium atom forms an ionic compound with two iodine atoms. Thus, the resulting molecular formula of barium iodide can be given as BaI2.
General Characteristics of Barium Iodide
Barium Iodide, represented by the molecular formula as BaI2, is an ionic compound and is found in both anhydrous form and as a hydrate. The chemical formula of barium iodide in the hydrate form is given as BaI2(H2O)2. Both of the forms of the compound are solids and have white colour. The anhydrous form can be easily obtained by heating the hydrate. It is well established that the hydrated form of barium iodide is soluble in water, ethanol and acetone.
The molecular weight of the anhydrous form as determined by the formula of barium iodide is 391.136 g/mol. Similarly, the molar mass of the hydrated form as can be calculated from the barium iodide formula is 427.167 g/mol. The properties of barium iodide and other halide compounds of barium are similar because they also are formed by the donation and subsequent acceptance of the electron. This is also visible from the commonality in their molecular formula. For example, the molecular formula of Barium Fluoride BaF2 is the same as the barium iodide formula with the change of iodine to fluorine.
As already mentioned, Barium iodide exists as a solid in both forms - the anhydrous and the hydrated form. It exists as a crystal and has an orthorhombic crystalline structure. The crystal structure of the anhydrous form of barium iodide resembles that of Lead (II) Chloride where instead of the lead ion, barium ion is present in the centre of the crystal structure and is bound to nine iodide ligands. The similarity in the structure can be because of both lead and barium being heavy metals. The crystalline packing of barium iodide structure also shares similarity with the crystalline form of Barium Chloride (BaCl2). The image of the crystalline packaging of barium iodide with barium being in the centre surrounded by nine iodine atoms as ligands are shown below:
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Some of the Main Chemical Reactions of Barium Iodide are Summarized Below:
The usual method of preparation of anhydrous form of Barium Iodide is by the reaction of barium metal with 1,2-diiodoethane. This reaction takes place in a solution made up of ether.
Barium iodide is known to form organometallic compounds that are of particular research interest. Barium Iodide reacts with compounds of alkyl potassium in order to form the corresponding organobarium compounds.
Barium Iodide is known to undergo reduction with lithium biphenyl which produces a highly reactive form of Barium as a reaction product.
Uses of Barium Iodide
Barium iodide is toxic in nature just like other soluble salts containing barium. It has very limited uses as compared to many other halide forms. Some of the uses of barium iodide include the following:
It can be used for the preparation of Barium dioxide, but as such has no further currently known purposes. Also, there is no biological relevance of barium dioxide.
It is used for the production of other iodide compounds.
It can also be used for the identification of copper castings as has been pointed out by some researchers.