The rates of oxidation of Cu(I) in air saturated solutions was measured as a function of pH, temperature (5-45°C), and ionic strength (0.5 to 6m) in NaCl and NaCl-NaClO4 solutions. In pure NaCl solutions, the effect of pH is independent of ionic strength and temperature. The overall rate constant is given by logk=12.32+0.12(pH)-2064/T-3.69I1/2+ 0.73I The energy of activitation was 39±2 kJ-mol-1 and is independent of ionic strength. At a constant ionic strength (I=1, 3 and 6m) in NaCl-NaClO4 mixtures the Cl- dependence of the rates is attributed to the oxidation of the various forms of Cu(I) in the solution. The rate constants for the oxidation of the various species are found to be functions of ionic strength. At a constant ionic strength (I=1) in NaCl-NaClO4 solutions, the effect of temperature is independent of the chloride concentration. The effect of Mg2+ and HCO3- on the oxidation rate was determined as a function of chloride concentration (1 to 6m) at 25°C and pH=8. The addition of Mg2+ causes the rate to decrease and the addition of HCO3- causes the rate to increase. The possible causes of these effects are discussed. Empirical equations for the rate of oxidation of Cu(I) in Na-Mg-Cl-HCO3 solutions as a function of composition are used to make reliable estimates of the oxidation in seawater and Red Sea waters.
- NaCl solutions
- ionic strength
ASJC Scopus subject areas
- Molecular Biology
- Physical and Theoretical Chemistry