Solubility

[bmuncy]

Hello,

 

Is there a way to plug in my temperature and pressure and see what the solubility for calcite is? Resulting with just a number, so and so concentration etc.

[Brian Farrell]

Hi,

 

Solubility can depend on a number of factors besides just temperature and pressure. Depending on the particular mineral, the pH, oxidation state, or the concentration of various complexing species in solution might affect solubility. You might use SpecE8 to solve for the composition of a fluid in equilibrium with Calcite at a given temperature. You swap Calcite in for one of the species from which it is formed (Ca++, HCO3- or CO3--, H+). Try starting with a simple solution first. When looking at the output, I would pay attention to the carbonate and calcium components in the fluid as well as the individual species themselves to see which are the most important.

 

You'll find a number of topics in the forum regarding the handling of pressure in the GWB.

 

Hope this helps,

 

Brian Farrell

Geochemist

Aqueous Solutions LLC

[bmuncy]

Thank you for your help. Do I need to create my own thermodynamic dataset or is there one within the program I just customize?

[Brian Farrell]

There are a number of thermodynamic datasets distributed with the GWB. You can read about a few of them here. If you need to add species to a dataset or modify equilibrium constants, you can use a text editor like Notepad or the TEdit thermo data editor in GWB10. The GWB Reference Manual, accessible from the Help menu of any GWB app, describes the organization of thermo datasets.

 

Hope this helps,

Brian