The FThelg solution database contains infinite dilution properties for over 1400 aqueous solute species taken from the GEOPIG-SUPCRT Helgeson public database.   These incorporate the Helgeson equation of state for temperatures up to 350oC and pressures up to 165 bar.


The solution FThelg-AQID assumes an ideal dilute solution and is generally valid up to approximately 0.001 molal.

The solution FThelg-AQDH incorporates the Debye-Huckel equation, and is generally valid up to approximately 0.02 molal.

The solution FThelt-AQDD incorporates the extended Debye-Huckel (Davies) equation and is generally valid up to 0.5 molal.


Clearly, only one of these three solutions should be chosen for any given calculation.




In addition, the FThelg pure compound database contains data for 185 pure solid compounds and gases which are thermodynamically consistent with the FThelg aqueous solution database.