barium carbonate

Barium carbonate is the inorganic compound with the formula BaCO3. Like most alkali metal carbonates, it is a white salt that is poorly soluble in water. It occurs as the mineral known as witherite. In a commercial sense, it is one of the most important

barium

compounds.

Preparation

Barium carbonate is made commercially from barium sulfide with by treatment with

sodium carbonate

at 60 to 70 °C (soda ash method) or, more commonly

carbon dioxide

at 40 to 90 °C:

In the soda ash process, an aqueous solution of barium sulfide is treated with sodium carbonate:
:BaS + H₂O + CO₂ → BaCO₃ + H₂S

Reactions

Barium carbonate reacts with acids such as

hydrochloric acid

to form soluble barium salts, such as

barium chloride

:
: + 2 HCl → + +

Pyrolysis of barium carbonate gives barium oxide.

Uses

It is mainly used to remove sulfate impurities from feedstock of the chlor-alkali process. Otherwise it is a common precursor to barium-containing compounds such as ferrites.

Other uses

Barium carbonate is widely used in the ceramics industry as an ingredient in glazes. It acts as a flux, a matting and crystallizing agent and combines with certain colouring oxides to produce unique colours not easily attainable by other means. Its use is somewhat controversial since some claim that it can leach from glazes into food and drink. To provide a safe means of use, BaO is often used in fritted form.

In the brick, tile, earthenware and pottery industries barium carbonate is added to clays to precipitate soluble salts (

calcium sulfate

and

magnesium sulfate

) that cause efflorescence.

References

External links

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Barium compounds
Carbonates
Pyrotechnic colorants