Determination of Goslarite–Bianchite Equilibria by the Humidity-Buffer Technique at 0.1 MPa

Authors

I-Ming Chou, 954 National Center, U.S. Geological Survey, Reston, Virginia 20192, U.S.A.Follow
Robert R. Seal II, 954 National Center, U.S. Geological Survey, Reston, Virginia 20192, U.S.A.

Date of this Version

2005

Comments

Published in Chemical Geology 215 (2005) 517– 523.

Abstract

Goslarite–bianchite equilibria were determined along four humidity-buffer curves at 0.1 MPa and between 27 and 36 °C. Results, based on tight reversals along each humidity buffer, can be represented by ln K (±0.005)=19.643-7015.38/T, where K is the equilibrium constant and T is temperature in K. Our data are in excellent agreement with several previous vapor-pressure measurements and are consistent with the solubility data reported in the literature. Thermodynamic analysis of these data yields 9.634 (±0.056) kJ mol^-1 for the standard Gibbs free energy of reaction, which is in good agreement with the value of 9.658 kJ mol^-1 calculated from the thermodynamic data compiled and evaluated byWagman et al. [Wagman, D.D., Evans, W.H., Parker, V.B., Schumm, R.H., Halow. I., Bailey, S.M., Churney, K.L., Nuttal, R.L., 1982. The NBS tables of chemical thermodynamic properties. Selected values for inorganic and C₁ and C₂ organic substances in SI units.