Zur Thermodynamik der Metallcarbonate 1. Mitteilung. Löslichkeitskonstanten und Freie Bildungsenthalpie von Cadmiumcarbonat, ein Beitrag zur Thermodynamik des ternären Systems Cd aq 2+ ‐H 2 O ( l ) ‐CO 2( g )

The equilibrium constant of the reaction CdCO 3( s ) + 2H + = Cd 2+ + H 2 O + CO 2( g ) has been determined at 25° in solutions of the constant ionic strength 3 M (Na)ClO 4 . With log* Kps 0 = 6,47 ± 0,15 the free enthalpies of H 2 O, CO 2( g ) and Cd   aq 2+yield −161,17 ± 0,20 kcal for the free enthalpy of the reaction Cd ( s ) + C ( s ) + 3/2 O 2( g ) = CdCO 3( s ) . A predominance diagram of the ternary system Cd   aq 2+− H 2 O ( l ) − CO 2( g ) is given.