Barium sulfite

Barium Sulfite can be prepared by reacting sodiumsulfite with bariumchloride:
BaCl2＋ Na2SO3→BaSO3＋ 2NaCl
Barium Sulfite occurs as white, monoclinic crystals with a density of 4.44 g/cm3. Its solubility in water is low (0.001125 g/100 ml) and it is insoluble in ethanol. When heated, it decomposes at 480°C to the oxide and SO2 gas.
It has been used as a weighting material on oil-drilling rigs to prevent “blow out” during drilling operations. This salt is used for such purposes, presumably because of its ability to absorb SO2 and H2S gases trapped in the rocks as drilling proceeds. The demand for barium sulfite is low.
Barium sulfite is available in limited quantities, commercially.