Rubidium hydrogen sulfate

Rubidium hydrogen sulfate

rubidium ion
hydrogen sulfate ion
Identifiers
CAS Number	15587-72-1
Properties
Chemical formula	RbHSO4
Molar mass	182,54 g/mol^−1
Appearance	Crystals with no colour[1]
Density	2.89 g·cm^−3
Melting point	214 °C (417 °F; 487 K)[2]
Related compounds
Other cations	rubidium oxide rubidium hydroxide
Related compounds	rubidium sulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Rubidium hydrogen sulfate is the rubidium salt of sulfuric acid. It has the formula RbHSO₄.

Synthesis

It may be synthesised with water and a stoichiometric amount of rubidium disulfate. Reaction takes place where there is no humidity: ^[3]

$\mathrm{Rb_2S_2O_7 + H_2O \longrightarrow 2\ RbHSO_4}$

There is an other method of creation. It is similar to the synthesis of sodium sulfate and potassium sulfate. For this reaction there need for rubidium chloride and a little bit warm sulfuric acid. Some hydrogen chloride is also produced during the reaction.

$\mathrm{ H_2SO_4 + \ RbCl \longrightarrow\ RbHSO_4 + \ HCl}$

Properties

It is a hydroscopic compound. It has a monocline crystal structure, its structure is P2₁/n. Parameters of the bonding modes: a = 1440 pm, b = 462,2 pm, c = 1436 pm and β = 118,0°. Its crystals are isomorphs with ammonium hydrogen sulfate crystals. ^[4]

Its standard enthalpy is −1166 kJ/mol ^[5] During its dissolution in water there is 15.62 kJ/mol energy produced. ^[6]

After warming up it resolves to rubidium disulfate and water:^[7]

$\mathrm{2\ RbHSO_4 \longrightarrow Rb_2S_2O_7 + H_2O}$

Like potassium and caesium, rubidium has an other hydrogene sulfate compound as well: Rb₃H(SO₄)₂.

Sources

1. Jean D'Ans, Ellen Lax: Taschenbuch für Chemiker und Physiker. 3. Elemente, anorganische Verbindungen und Materialien, Minerale, Band 3. 4. Auflage, Springer, 1997, ISBN 978-3-5406-0035-0, S. 692 (Taschenbuch für Chemiker und Physiker, p. 692, at Google Books).
2. R. Fehrmann, S. Boghosian, H. Hamma-Cugny, J. Rogez: "Phase diagrams, structural and thermodynamic properties of molten salt solvents for the industrial SO₂-oxidation catalyst" Abstract
3. S. B. Rasmussen, H. Hamma, K. M. Eriksen, G. Hatem, M. Gaune-Escard, R. Fehrmann: "Physico-chemical properties and transition metal complex formation in alkali pyrosulfate and hydrogen sulfate melts". VII International Conference on Molten Slags Fluxes and Salts, The South African Institute of Mining and Metallurgy, 2004. Volltext (PDF; 661 kB)
4. J. P. Ashmore, H. E. Petch: "The Structure of RbHSO₄ in its Paraelectric Phase" in Can. J. Phys 1975, 53(24), S. 2694-2702. doi:10.1139/p75-328
5. L. A. Cowan, R. M. Morcos, N. Hatada, A. Navrotsky, S. M. Haile: "High temperature properties of Rb₃H(SO₄)₂ at ambient pressure: Absence of a polymorphic, superprotonic transition" in Solid State Ionics 2008, 179, S. 305-313. Volltext (PDF; 837 kB)
6. M. de Forcrand: "Sur les chlorures et sulfates de rubidium et de caesium" in Compt. Rend. Hebd. 1906, 143, S. 98. Volltext
7. R. Abegg, F. Auerbach: "Handbuch der anorganischen Chemie". Verlag S. Hirzel, Bd. 2, 1908. S. 432.Volltext