Double salt

Double salts are salts thereof with a plurality of different cations, or different anions.

They arise when in a solution of two different salts are dissolved and these crystallize together in a regular crystal structure. In contrast to complex salts dissociate in aqueous solution into its individual ions. Their physical properties such as electrical conductivity, put in an additive manner together from their individual components.

A well-known class of compounds of the double salts are of the general formula alums Mimiii (SO4) 2 · 12 H 2 O ( wherein MI is a monovalent and a trivalent cation MIII ); named after alum, the usual common name for aluminum potassium sulfate dodecahydrate ( KAl ( SO4) 2 · 12 H2O).