Plotting More Pourbaix Diagrams

When you have calculated a Pourbaix diagram, you can plot additional diagrams based on the results of the same calculation, but with different axis variables than Ph and Eh.

The variables can be plotted along the X- and Y-axes. Use the abbreviations of the variables when you specify what the X- and Y-axes represent in a diagram. In the table, AQsp refers to the name of a specific aqueous species. The asterisk (*) can be used as a wild card character for all such species. If neither AQsp nor * is entered in parenthesis, then all species are searched.

You must have plotted a Pourbaix diagram to plot a diagram with other variables than Ph and Eh on the Y-axis and the X-axis. You can either plot such additional diagrams directly after having finished the plotting and saving/printing of a Poubaix Ph-Eh diagram or by choosing option 2 (Open an old file and plot other property diagrams) when you enter the POURBAIX module and opening a POLY3 workspace file.

Abbreviation Variable

pH

Acidity

Eh

Electronic Potential (V)

Ah

Electronic Affinity  (kJ)

Pe

Electronic Activity (log10ACRe)

IS

Ionic Strength

TM

Total Concentration

Aw

Activity of Water

Oc

Osmotic Coefficient

MF(AQsp)

Mole Fractions of Aqueous Species

ML(AQsp)

Molalities of Aqueous Species

AI(AQsp)

Activities of Aqueous Species

RC(AQsp)

Activity Coefficients of Aqueous Species
  1. Type Y when prompted whether to plot any more diagrams, or select option 2 when you enter the POURBAIX module.
  2. Specify which variable you want the X-axis to represent. Use the abbreviation specified in the preceding table. When you specify the name of an aqueous species, you can use the asterisk (*) to select all species.
  3. Specify which variable you want the Y-axis to represent. The diagram is then automatically plotted.
  4. Answer questions about how the diagram is plotted and how to save it. You are asked to do any of the following:
    1. change the axis-type (linear, logarithmic or inverse) on the X-axis or Y-axis
    2. zoom in on a specific region of the diagram
    3. change the curve-label option for the diagram 
    4. add label-texts onto the Pourbaix diagram
    5. change the subtitle of the diagram
    6. change the axis-texts
    7. refine the diagram in the POST Module
    8. print the diagram (save a hard copy)
    9. save the X-Y coordinates of curve on a text file
    10. modify the plotted diagram
    11. calculate and plot another aqueous solution diagram