What Is Cesium Chloride?
Cesium chloride is an inorganic compound with the chemical formula CsCl.
In the laboratory, cesium chloride is obtained by treating cesium hydroxide, cesium carbonate, cesium bicarbonate, or cesium sulfide with hydrochloric acid.
Cesium chloride is not toxic to humans or animals; none of the GHS classifications apply to it. It is not regulated by the Industrial Safety and Health Law, the Labor Standards Law, the PRTR Law, or the Poisonous and Deleterious Substances Control Law.
Uses of Cesium Chloride
Examples of applications of cesium chloride include phototubes, photosensitive deposition films, phosphors, catalysts, optical fibers, chlorinating agents, and reagents for density gradient centrifuges. It can be used as a cesium ion source in the synthesis of other cesium compounds.
DNA separation reagents and vacuum tube materials are particularly unique uses of cesium chloride. As a radioactive isotope, cesium chloride is also used in scintigraphy. Scintigraphy is a diagnostic technique that detects and visualizes radiation from the administration of radioactive isotopes in the body.
Properties of Cesium Chloride
Cesium chloride has a melting point of 645°C and a boiling point of 1,295°C. It is a white crystal or crystalline powder.
Cesium chloride is deliquescent. When dissolved in water, it dissociates completely and Cs+ is solvated by a dilute solution.
Cesium chloride can be converted to cesium sulfate by heating it in concentrated sulfuric acid or with cesium hydrogen sulfate at 550-700°C. Cesium chloride forms various complex salts with other chlorides. Examples include 2CsCl・BaCl2, CsCl-2CuCl, 2CsCl-CuCl2, and CsCl-LiCl.
Structure of Cesium Chloride
Cesium chloride has a formula weight of 168.36 g/mol and a density of 3.99 g/cm3.
The solid is an ionic crystal, a simple cubic lattice composed of chloride ions (Cl−) and cesium ions (Cs+). Each chloride ion is flanked by eight cesium ions; a salt crystal with a composition ratio of 1:1 takes on a cesium chloride-type structure when the radii of the two types of ions are approximately equal. The cesium chloride-type structure is one of the typical structures of ionic crystals. Besides cesium iodide and cesium bromide, other compounds known to form cesium chloride-type structures include copper-zinc and iron-rhodium 1:1 alloys.
Cesium chloride has a lattice constant of a = 0.411 nm and an interatomic distance Cs-Cl of 0.345 nm.
Other Information on Cesium Chloride
1. Cesium Chloride in Nature
Cesium chloride occurs naturally as an impurity in the halogenated minerals carnallite (KMgCl3・6H2O containing up to 0.002% CsCl), potash rock salt (KCl), kainite (MgSO4・KCl・3H2O), and mineral water. For example, the water in the spa in Bad Durkheim used for cesium separation contained about 0.17 mg/L of cesium chloride.
2. Method of Synthesizing Cesium Chloride
Industrially, cesium chloride can be purified by dissolving cesium carbonate in hydrochloric acid and recrystallizing it. Cesium chloride is produced from Pollucite, and when the extract is treated with antimony chloride, iodine monochloride, or cerium(IV) chloride, it is formed as an insoluble double salt. Hydrogen sulfide yields cesium chloride. Recrystallization of pyrolyzed Cs[ICl2] or Cs[ICl4] can produce high-purity cesium chloride.
3. Hazards of Cesium Chloride
The median lethal dose (LD50) of cesium chloride in mice is 2,300 mg per kg body weight by oral administration and 910 mg/kg by intravenous injection. Cesium chloride partially displaces potassium, thus decreasing potassium levels in the body. Large doses of cesium chloride can cause potassium imbalance, resulting in hypokalemia, arrhythmia, and acute cardiac arrest.