Jump to content
Geochemist's Workbench Support Forum

pH calculation


rawls423

Recommended Posts

Hi,

 

I have the following information and am wondering if it is possible to calculate the pH. I do not know anything more specific about the alkalinity. All concentrations are mg/L. The sample is open to the atmosphere

 

Ba ++ 383
Ca ++ 2438
Fe ++ 5.904
K+ 109.1
Li+ 24.9
Mg++ 238
Mn++ 1.672
Na+ 11786.4
SiO2 (aq) 42.55
Sr++ 431.2
Cl- 23100.0
SO4-- 35.5
Br- 263
NO3- 17.9
Carbonate Alkalinity 292 mg/L as CaCO3

 

Thank you!

Link to comment
Share on other sites

Hi,

 

The GWB programs require you to set pH explicitly when using the alkalinity to constrain the total carbonate component concentration. Typically when you measure alkalinity you should measure the initial pH as well. Autotitrators that record pH as acid is added are really nice for this.

 

If you had this information, you would use SpecE8 to add each of the above species to the Basis pane and set their values with mg/l units. For HCO3-, you would set the concentration to 292 with units mg/l_as_CaCO3. For H+, you would choose pH units.

 

Since you know the fluid is open to the atmosphere, you might guess the pH and run the equilibrium model to determine the CO2 fugacity. Use trial and error to find a pH that yields a log CO2 fugacity of -3.5.

 

Hope this helps,

 

Brian Farrell

Geochemist

Aqueous Solutions LLC

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...
×
×
  • Create New...