Because barium sulfate is opaque to X-rays, it is suspended in water and taken internally to make the gastrointestinal tract visible in an X-ray photograph. Although barium ion is quite toxic, barium sulfate’s Ksp of 1.1 x 10–10 gives it such low solubility that it can be safely consumed.
(a) What is the molar solubility of BaSO4?
(b) What is its solubility in grams per 100 g of water?
