Thermodynamic Properties of Aqueous Arsenic Species and Scorodite Solubility

An internally consistent thermodynamic network for arsenic minerals and aqueous species is being developed based on a high quality starting point: arsenolite and arsenolite solubility. Current research is refining the properties of scorodite solubility as a function of temperature along with improved aqueous species stability constants and activity coefficients for ions and ion pairs based on potentiometric measurements of redox, pH, and conductivity for 5-90 °C. The second and third hydrolysis constants for arsenic acid have been calculated as a function of temperature and thermodynamic properties have been derived.