定义Definition
硫酸钡 BaSO₄ 是白色固体，几乎不溶于水和稀酸，溶度积约 1.1 × 10⁻¹⁰。天然矿物为重晶石。它不被 X 射线穿透，又因不溶而无毒，可作“钡餐”用于消化道造影；BaSO₄ 的生成也是检验硫酸根的依据。
Barium sulfate, BaSO₄, is a white solid almost insoluble in water and dilute acids, with a solubility product of about 1.1 × 10⁻¹⁰; it occurs naturally as baryte. It is opaque to X-rays and, being insoluble, is not toxic, so it is used as a 'barium meal' for imaging the digestive tract. Its formation is also the basis of the test for sulfate ions.
为什么钡餐安全Why a barium meal is safe
可溶性钡盐（如 BaCl₂）中的 Ba²⁺ 有毒，而 BaSO₄ 溶解度极小，进入人体的 Ba²⁺ 很少，因此可以安全服用。碳酸钡不能代替，因为它会溶于胃酸放出 Ba²⁺。
Ba²⁺ from soluble barium salts such as BaCl₂ is toxic, but BaSO₄ is so insoluble that very little Ba²⁺ is absorbed, so it can be swallowed safely. Barium carbonate cannot be used instead, because stomach acid dissolves it and releases Ba²⁺.
其他用途Other uses
用作白色颜料和填料（涂料、塑料、纸张），以及石油钻井泥浆的加重剂（密度约 4.5 g cm⁻³）。
It is used as a white pigment and filler in paints, plastics and paper, and as a weighting agent in oil-well drilling mud (density about 4.5 g cm⁻³).
化学性质Chemical properties
生成：Ba²⁺ + SO₄²⁻ → BaSO₄
Formation: Ba²⁺ + SO₄²⁻ → BaSO₄