bcarey Posted January 24, 2011 Share Posted January 24, 2011 I am trying to develop a consistent thermodynamic database for Al-hydroxides and noticed the following in thermo.com.v8.r6 I am trying to verify that I am using SUPCRT92 correctly by comparing SUPCRT92 output with the thermo.com.v8.r6 database. This database uses Pokrovskii and Helgeson 1995 (American Journal of Science) for the Al-H2O system. SUPCRT92 has sprons96.dat which also uses Pokrovskii and Helgeson 1995. The SUPCRT92 calculated log K values for Gibbsite, Boehmite and Diaspore agree at 25 but disagree at other temperatures to varying degrees (See Table below). Other minerals are exactly consistent, for example, anorthite. Anyone know why or how these values are different? Log K values Gibbiste Temp thermo.com SUPCRT 25 C 7.756 7.756 300 C -2.4754 -1.368 Boehmite Temp thermo.com SUPCRT 25 C 7.5642 7.564 300 C -2.7773 -2.705 Diaspore Temp thermo.com SUPCRT 25 C 7.1603 7.160 300 C -2.8906 -2.865 Anorthite Temp thermo.com SUPCRT 25 C 26.578 26.578 300 C -2.5408 -2.541 According to the GWB thermo.com.v8.r6 database header, they use supcrt as the "extrapolation algorithm (at least for these phases). Quote Link to comment Share on other sites More sharing options...
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