many thanks for your kind respond, I found this program interesting , but it does not work on my computer. did you manage to use this software? if yes, can you please inform me how it is work as it is not activated on my computer?
I know this is very late to the game, but the only user-friendly interface I'm used to is Geochemist's Workbench, which is not free. The PhreePlot paper (Kinniburgh and Cooper, 2004) is compelling, but as noted above, it's a pain to learn (I have not made time to do it yet). There's always the option of using the thermodynamic formulas in Excel to do it manually (which sucks, I know).