The Solubility of Malachite

Abstract

The solubility at 25 °C. of the sparingly soluble basic copper carbonate malachite has been determined by two methods. The constancy of the calculated value of the solubility product in solutions of varying ionic strength has shown it to be a comparatively well-defined material suitable for the study of the complexing ability of various organic chelating compounds. Evidence is presented for the existence of a cupric ion – carbonate ion complex under appropriate pH conditions.

Solid–solute phase equilibria in aqueous solution. XVI. Thermodynamic properties of malachite and azurite—predominance diagrams for the system Cu 2+– H2 O– CO 2

“…The experimental results for malachite obtained by Scaife (7) are re-evaluated by taking into account the complexes CuHCO (table 4), resulting in log K 0 ps0 (mal.) = 6.65 at T = 298.15 K (filled square in figure 2).…”

“…Among others, Scaife, (7) Silman, (8) Schindler et al (9) and Stella and GanzerliValentini (10) determined the solubility constant of malachite at T = 298.15 K. Free (11) investigated the solubility of malachite at T = 303.15 K and Symes and Kester (12) obtained this quantity in the temperature range from T = 278.15 K to T = 298.15 K. The solubility of azurite was studied by Silman (8) and Schindler et al (9) at T = 298.15 K.…”

Thermodynamic properties of copper carbonates ? malachite Cu2(OH)2CO3 and azurite Cu3(OH)2(CO3)2

“…Published thermodynamic data for malachite and azurite are mostly limited to equilibrium constants in aqueous solutions (Garrels 1957;Scaife 1957;Silman 1958;Reinert 1965;Schindler et al 1968). Table 1 summarizes the reported values of In Kaiss for malachite and azurite, and shows their great variation.…”

“…Table 1 summarizes the reported values of In Kaiss for malachite and azurite, and shows their great variation. These discrepancies may result from the malachite samples being too fine-grained (Scaife 1957), from the lack of equilibrium (Silman 1958), from the use of impure solid phases (Symes and Kester 1984), or from uncertainties in activity coefficients of aqueous species.…”

Etude cinétique de la complexation du cuivre en milieu hydrogénocarbonate par électrochimie

“…-Réactions de précipitation : les deux solides dont la formation est possible en milieu carbonate, sont Thydroxyde de cuivre et la malachite (SCAIFE, 1957 ;. Nous avons pu montrer ainsi que les concentrations en cuivre que nous utilisons sont bien en dessous du seuil de précipitation de ces deux solides.…”