Double salts
Double salts are salts with several different cations or different anions .
They arise when two different salts are dissolved in a solution and they crystallize together in a regular crystal structure . In contrast to complex salts , they dissociate into their individual ions in aqueous solution . Their chemical properties therefore correspond to those of their individual components. The same applies z. B. for electrical conductivity .
A known class of compound of double salts are the alums with the general formula M I M III (SO 4 ) 2 · 12 H 2 O (where M I stands for a monovalent and M III for a trivalent cation); named after alum, the common trivial name for aluminum potassium sulfate dodecahydrate (KAl (SO 4 ) 2 · 12 H 2 O).
Another series of double salts of the type M I 2 M II (SO 4 ) 2 · 6 H 2 O (where M I stands for a monovalent and M II for a divalent cation) are called Tutton salts . The best-known representative is Mohr's salt ( ammonium iron (II) sulfate ).
literature
- Riedel, Janiak: Inorganische Chemie , 7th edition, de Gruyter, Berlin 2007, ISBN 978-3-11-018903-2 , p. 593.
- Wilhelm Hofmann: Journal of Crystallography - Crystalline Materials , Volume 78, Issue 1, December 1931, pp. 279–333; doi : 10.1524 / zkri.1931.78.1.279 .