Jump to content
Geochemist's Workbench Support Forum

GWB > Pitzer parameters alpha1/alpha2


bine
 Share

Recommended Posts

Hello Tom,

 

I have a question regarding the treatment of the Pitzer parameters alpha1 and alpha2 in GWB.

In Craig`s book "Geochemical and Biogeochemical Reaction Modeling" (2nd edn) I find the following

equation in Table 8.1 on page 125 (under step 4):

 

BMX = beta0 + beta1 * g * (alpha1 * sqrt(I)) + beta2 * g * (12 * sqrt(I))

 

Is it correct, that the "12" represents the value of alpha2 and is it fixed to that value for

every possible cation-anion pair? This would imply that the alpha2 values given in the parameter

file are not really used?

 

Thanks a lot for your help,

Christiane

Link to comment
Share on other sites

Dear Christiane:

 

The book uses a constant value because the parameter value is 12 for all cation-anion pairs (you can see this by inspecting the two Pitzer databases GWB uses, thermo_hmw.dat and thermo_phrqpitz.dat). The GWB code, however, picks up alpha_MX^(2) directly from the thermo dataset- so you can change these parameters to anything you want, and it will be reflected in the 2nd virial coefficient calculations.

 

I hope that helps,

 

Tom

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...