Debye-Huckel coefficients in thermo.dat

[natasha543]

Hi all,

 

I'm trying to calculate A and B using the expression given in Helgeson(1969). The values I get seem to be quite off from the values given in the database and in Helgeson(1969). I think it's because my water density and dielectric constant calculations are wrong. Does anyone know what water densities and dielectric constants (as a function of temperature) were used to calculate A(T) and B(T) in thermo.dat?

 

Also, I notice in thermo.dat that B(T) is tabulated without a factor of 10^8. Is this factored in by GWB or am I misunderstood in thinking that the coefficients B have a magnitude of 10^8?

 

Many thanks,

 

Natasha

[Benjamin]

You are correct about the factor of 10^8 on B. GWB tabulates them without the factor, but they are indeed all multiplied by 10^8 in the calculations. To calculate A and B, I would suggest using: Helgeson, H. C., Kirkham, D. H., 1974b. Theoretical prediction of the thermodynamic behavior of aqueous electrolytes at high pressures and temperatures: II. Debye-Huckel parameters for activity coefficients and relative partial molal properties. Am. J. Sci. 274 (10), 1199–1261.

 

Density and dielectric constants are calculable using algorithms implemented in SUPCRT92 (Johnson et al, 1992).