WebElements Periodic Table of the Elements | Caesium

Caesium compounds: caesium chloride

The caesium in caesium chloride formally is in the oxidation state 1.

Caesium chloride

Formula as often written: CsCl
Hill system formula: Cl₁Cs₁
CAS registry number: [7647-17-8]
Formula weight: 168.358
Class: chloride

Synonyms

caesium chloride
caesium(I) chloride
cesium chloride
cesium(I) chloride

Physical properties

Colour: white
Appearance: crystalline solid
Melting point: 646°C
Boiling point: 1290°C; 1297°C
Density: 3988 kg m^-3

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Element analysis

Element percentages for the elements in caesium chloride
Element	%
Cl	21.06
Cs	78.94

Synthesis

One way to make caesium chloride is to react the hydroxide with hydrochloric acid. The resulting salt can then be purified by recrystallization.

CsOH(aq) + HCl(aq) → CsCl(aq) + H₂O(l)

Caesium(I) chloride can also be made by the neutralization of caesium(I) carbonate with hydrochloric acid. The resulting salt can then be purified by recrystallization.

Cs₂(CO₃)(aq) + 2HCl(aq) → 2CsCl(aq) + H₂O(l) + CO₂(g)

While not a normal route of preparation because of the expense, caesium metal reacts vigorously with all the halogens to form sodium halides. So, it burns with chlorine, Cl₂, to form caesium(I) chloride, CsCl.

2Cs(s) + Cl₂(g) → 2CsCl(s)

Solid state structure

Geometry of caesium: 8 coordinate: cubic
Prototypical structure: CsCl

Crystal structure of caesium chloride

Isotope pattern

What follows is the calculated isotope pattern for the CsCl unit with the most intense ion set to 100%.

Formula: Cs₁Cl₁

mass  %
168 100.0 __________________________________________________
169   0.0 
170  32.0 ________________

References

The data on these compounds pages are assembled and adapted from the primary literature and several other sources including the following.

R.T. Sanderson in Chemical Periodicity, Reinhold, New York, USA, 1960.
N.N. Greenwood and A. Earnshaw in Chemistry of the Elements, 2nd edition, Butterworth, UK, 1997.
F.A. Cotton, G. Wilkinson, C.A. Murillo, and M. Bochmann, in Advanced Inorganic Chemistry, John Wiley & Sons, 1999.
A.F. Trotman-Dickenson, (ed.) in Comprehensive Inorganic Chemistry, Pergamon, Oxford, UK, 1973.
R.W.G. Wyckoff, in Crystal Structures, volume 1, Interscience, John Wiley & Sons, 1963.
A.R.West in Basic solid state chemistry Chemistry, John Wiley & Sons, 1999.
A.F. Wells in Structural inorganic chemistry, 4th edition, Oxford, UK, 1975.
J.D.H. Donnay, (ed.) in Crystal data determinative tables, ACA monograph number 5, American Crystallographic Association, USA, 1963.
D.R. Lide, (ed.) in Chemical Rubber Company handbook of chemistry and physics, CRC Press, Boca Raton, Florida, USA, 77th edition, 1996.
J.W. Mellor in A comprehensive treatise on inorganic and theoretical chemistry, volumes 1-16, Longmans, London, UK, 1922-1937.
J.E. Macintyre (ed.) in Dictionary of inorganic compounds, volumes 1-3, Chapman & Hall, London, UK, 1992.