| Abstract: | Equilibrium constants for copper(II)-carbonate and -bicarbonate species have been determined at 25°C from consideration of malachite, Cu2(OH)2CO3(s), solubility in UV-photo-oxidized perchlorate solutions of 0.72 m ionic strength. The ratios of total dissolved copper, T(Cu), to free copper(II) ion, Cu 2+], in 30 malachite saturated experimental solutions of 1–10 × 10?3eq kg?1 H2O initial total alkalinity (TAi in the pH range 5.0–9.3 were fitted to a copper(II)-ion speciation model. The experimental data indicate the existence of CuCO3+, CuHCO3+ and Cu(OH)CO3? in addition to the hydrolys and Cu(OH)CO3? in addition to the hydrolysis products in the range of conditions defined by this study. The stoichiometric equilibrium constants, applicable to seawater at 0.72 m ionic strength, 25°C and 1 atm are A speciation model employing the equilibrium constants determined in this study and copper(II) hydrolysis constants from previous work suggests that the inorganic speciation in seawater (pH = 8.2, TA = 2.3 meq kg ?1, 25°C) is dominated by the CuCO30 complex (82%) and that only 2.9% of the total inorganic copper exists as the free copper(II) ion. Hydrolysis products, CuOH+ and Cu(OH)20, account for 6.5% while CuHCO3+ and Cu(OH)CO3? species comprise 1.0 and 6.3% of the total inorganic copper, respectively. |
