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saturation of KI in H2O at 50 degree C and 100 Bar


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Hello to all,

 

I am a complete beginner and my background is not that good in geochemistry but alas I need to use it in parts of my PhD.

 

Basically, all I want to do is have the Geochemist's Workbench calculate for me the amount in grams of potassium iodide (KI) it will take to fully saturate a liter of water at 50 C temp and 100 Bar pres.

 

I would love to learn how to navigate and use this software because it will be very useful in my PhD involving reactive transport. Before buying the full version I want to at least be able to use it.

 

Thanks to all replies in advance.

 

Yousef

 

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Hello Yousef,


There’s no KI mineral in any of the thermodynamic datasets installed with the software but you can easily add a new mineral to a thermo dataset. To do so, you’ll need an equilibrium constant corresponding to a reaction to form the mineral from species in the dataset (eg. KI = K+ + I-). You would need at least two log K’s at 25°C and 60°C (assuming you’re working with the default dataset – thermo.tdat, which uses those default temperatures) to work at 50°C, and the more data you have the better. You can use the TEdit program (under the support tab on the GWB dashboard) to modify a dataset in this way. It’s always a good idea to start by opening an existing dataset and saving it to a different name before modifying it in some way. For more information, see the TEdit section in the GWB Essentials Guide (you can access PDFs of the user's guides from the Help menu of any GWB program, or from the Docs pane of the GWB dashboard). You can also view tutorials on how to edit thermo datasets here.


The GWB programs operate within the temperature range of the thermo dataset currently loaded. The default thermodynamic dataset thermo.dat contains log K entries compiled along the steam saturation curve from 0°C to 300°C. You can use a thermo dataset compiled at the pressure of interest, but hydrothermal chemists not uncommonly assume the effects of confining pressure are small compared to the uncertainty in determining log Ks and activity coefficients. Note, however, that gas partial pressures are almost invariably significant. You account for the partial pressure of a coexisting gas by setting its fugacity.


Before you find the KI thermo data, you can take look at halite solubility using SpecE8. Add Na+ and Cl- ions to your initial system and swap halite in for one and constrain it with an arbitrary mass. You can set the other entry as a charge balancing ion. Set your temperature of interest and run your model. For more information, see Using SpecE8 in the GWB Essentials Guide.


Kind regards,


Katelyn

Aqueous Solutions LLC

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