Cadmium carbonate, dissociation

Cadmium carbonate behaves similarly to calcium carbonate and, on being heated, gives rise to the equilibrium CdCOg CdO + COg. The equilibrium pressure at different temperatures has been determined by Centnerszwer and Andrusov, who find that the dissociation pressures are expressed by the formula log = — 12 44 + 0 02439 T. The reaction CdO + COg CdCOg takes place about fihy times more slowly than the reaction CdCOg CdO + COg. 

Debray, in 1867, carried out the first measurements of the dissociation pressure of calcium carbonate. He heated Iceland Spar in a tube to the temperature of boiling mercury, sulphur, cadmium and zinc (357, 445, 767, 907 °C respectively). He found no decomposition at the first two, but measurable pressures at the boiling points of cadmium and zinc. The first exact measurements of the dissociation pressure were made by Le Chatelier in 1886. 

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