Caesium chloride
General
Other names	Cesium chloride
Molecular formula	CsCl
Molar mass	168.36 g/mol
Appearance	white solid
CAS number	*
EINECS number	231-600-2
Properties
Density and phase	3.99 g/cm3, solid
Solubility in water	162 g/100 ml (1 °C)
In methanol In ethanol In acetone	33.7 g/100 ml Very soluble Insoluble
Melting point	645°C
Boiling point	1295°C
Structure
Coordination geometry	simple cubic
Crystal structure	see text
Thermodynamic data
Supplementary data page
Structure & properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Other anions	Caesium fluoride Caesium bromide Caesium iodide
Other cations	Potassium chloride Rubidium chloride
Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Chemical infobox

Caesium chloride is an ionic compound best known as a structural type.

Preparation

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Caesium chloride can be prepared by the reaction of caesium hydroxide or caesium carbonate with hydrochloric acid: the resulting salt is purified by recrystallization.

Caesium metal reacts violently with chlorine gas to give caesium chloride, although the expense of metallic caesium means that this is not the usual route of preparation.

Crystal structure

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The caesium chloride structure is composed of interlocking simple cubic lattices of anions and cations. It is the case that in a cubic 1:1 solid where one atom type is much larger than the other that the cesium chloride type lattice is obtained, it can be thought of as a combination of footballs and golf balls packed in a cubic manner with the golf balls in the gaps between the footballs. If the two atom types are similar in size (imagine hockey balls packed with tennis balls) then in the cubic lattice the structure will be like that of sodium chloride.

Uses

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Caesium chloride is used in the preparation of electrically conducting glasses.

Radioisotopes of caesium chloride are used in nuclear medicine, including treatment of cancer. In the production of radioactive sources it is normal to choose a chemical form of the radioisotope which will not be dispersed with ease in the environment as a result of an accident where the source is smashed open. For instance radiothermal generators (RTGs) often use strontium titanate because it is insoluble in water. But for teletherapy sources the radioactive density (Ci in a given volume) needs to be very high, as a result it is not possible with any of the insoluble caesium compounds to create the source. As a result it is normal to use a thimble shaped can of radioactive caesium chloride to provide the active source in a teletherapy type radiotherapy unit. In Brazil such a source was stolen by scrap metal workers from a disused radiotherapy clinic, and serious injurys and deaths occurred as a result of external gamma exposure and internal exposure (the source was smashed open, releasing the water soluble cesium chloride). See the Goiânia accident for further details.

Reference

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1. Tver'yanovich, Y. S. et al. (1998). Glass Phys. Chem., 24, 446.

External links

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Caesium compounds | Chlorides | Metal halides

Cäsiumchlorid | Chlorek cezu