I am trying to plot Sb(III) speciation over pH as a function of sulfide, which itself speciates over pH (using Arc2). The x axis is pH and the y axis should be the sum of HS- and H2S concentrations. I have added the thermodynamc data for Sb sulfide complexes to the database, but sulfide does not speciate as HS-/H2S. I managed to plot Sb speciation with either HS- or H2S as the y axis and I have attached these files.
Could you please advise me if (and how) it is possible that sulfide speciates over pH (no redox reactions required) to merge the two diagrams into one?
Thanks a lot