Spana  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).

Diagram H+ / CO2

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 4 0 0
H+, CO2(g)
OH-,   -14.0   -1 0
H2CO3,  -1.468  0 1
HCO3-,  -7.82  -1 1
CO3 2-,-18.149 -2 1
LAC, -9 0 H+
LAV, -3 -9.7  LA, -3.5