Barium sulfate

Chemical Properties

Barium sulfate is a soft crystalline solid. Its density is 4.50 g/cm3 and its refractive index is 1.64. It melts around 1580 °C but decomposes above 1600 °C. Its hardness is 4.3 to 4.6 Mohs. It is virtually insoluble in water (285 mg/l at 30 °C) and insoluble in alcohol. Its Ksp is 1.1 × 10–10. It is soluble in concentrated sulfuric acid.

Physical properties

Barium sulfate is a white crystalline solid that is odorless and insoluble in water. It occurs as the mineral barite, which is the main commercial source of barium and materials prepared from it.

Uses

Barium sulfate is used to help diagnose or find problems in the esophagus, stomach, and bowels. It is a radiographic contrast agent. Contrast agents are used to create a clear picture of the different parts of the body.

Preparation

Barium sulfate, BaSO4, is made by reacting barium hydroxide and other barium sources with sulfuric acid and has a long history as a translucent white pigment.

Toxicity

Although soluble salts of barium are moderately toxic to humans, barium sulfate is nontoxic due to its insolubility. The most common means of inadvertent barium poisoning arises from the consumption of soluble barium salts mislabeled as BaSO4.

Structure and conformation

The crystal structure of Barium sulfate is known to be rhombic, with a space group pnma. The lattice parameters are: a = 8.896 Å, b = 5.462°, c = 7.171 Å, V = 348.4 Å3.