Electrolytes and Activity Coefficients
1. How does OLI calculate pH?
To see how the software calculates the pH, please see the following paper on Mo chemistry, Section 3: Solution chemistry of Mo(III) and Mo(IV): Thermodynamic foundation for modeling localized corrosion .
In short, the chemical potential is calculated for each species (base ions, hydrolyzed species, complexes, etc.) according to the following equation:
The chemical potential contains two contributions – the standard contribution (which is directly linked to equilibrium constants) and the activity coefficient from the MSE model. Then, the equilibrium reactions between all species are written and solved according to Equation 1. As always, the key to accuracy is the determination of parameters, which are also described in the paper referenced above.
