Colorless crystals, decomposes and reddens on exposure to air.Soluble in water; slightly soluble in alcohol.
Barium iodide occurs in two forms, one anhydrous
and the other as a dihydrate. Both are white solids. This salt is stable, but air and light sensitive. It is also
hygroscopic and moisture sensitive. Barium iodide is
incompatible with strong oxidizing agents.
Preparation of other iodides.
Barium
iodide is made by the neutralization of barium
carbonate with HI in water:
BaCO3＋2HI (aq)→BaI2 (aq)
It is also made by the reaction of BaH2 with ammonium
iodide in pyridine:
BaH2＋2NH4I (aq)→BaI2 (aq)＋ 2NH3 (gas)＋H2 (gas)
The product crystallizes as the hydrate BaI2·2H2O. If
this heated, dehydration to anhydrous BaI2 occurs. The
dihydrate dehydrates at 539°C to form BaI2.
