Rubidium compounds: rubidium chloride

rubidium symbol icon

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

Crystal structure of rubidium chloride

Rubidium chloride

  • Formula as often written: RbCl
  • Hill system formula: Cl1Rb1
  • CAS registry number: [7791-11-9]
  • Formula weight: 120.921
  • Class: chloride


  • rubidium chloride
  • rubidium(I) chloride

Physical properties

  • Colour: white
  • Appearance: crystalline solid
  • Melting point: 718°C; 718°C
  • Boiling point: 1390°C
  • Density: 2760 kg m-3


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Element analysis

Element percentages for the elements in rubidium chloride
Element %
Cl 29.32
Rb 70.68


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

RbOH(aq) + HCl(aq) → RbCl(aq) + H2O(l)

Rubidium(I) bromide can also be made by the neutralization of rubidium(I) carbonate with hydrobromic acid. The resulting salt can then be purified by recrystallization.

Rb2(CO3)(aq) + 2HBr(aq) → 2RbBr(aq) + H2O(l) + CO2(g)

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

2Rb(s) + Cl2(g) → 2RbCl(s)

Solid state structure

  • Geometry of rubidium: 6 coordinate: octahedral
  • Prototypical structure: NaCl (rock salt)

Crystal structure of rubidium chloride

Isotope pattern

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

Formula: Rb1Cl1

mass  %
120 100.0 __________________________________________________
121 0.0
122 70.5 ___________________________________
123 0.0
124 12.3 ______


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.

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rubidium atomic number