SPANA / Modify Chem. System

Example of a log activity diagram showing the activities (on a logarithmic scale) for all species in the system H⁺, CO₂(g). Note that the component CO₃²⁻ in DATABASE has been exchanged for a reaction, in this case for CO₂(g).

Note that for gases the fugacity (≈ partial pressure) is calculated and it is displayed. The calculations consider the aqueous phase only, and the concentrations for gases are set to zero and they are not displayed in a logarithmic diagram.

Note: “log activity diagrams” can only be created with the advanced program level selected in the menu “Preferences / General options” in SPANA.

The diagram displayed above was obtained with the following input file:

 2 5 0 0
H+, CO2(g)
CO2    , -1.472   0  1
H2CO3  , -4.247   0  1
HCO3-  , -7.825  -1  1
OH-    , -14.002 -1  0
CO3 2- , -18.152 -2  1
LAC,-9, 1, H+,
LAV, -1 -12  LA, -3.5