Erik S Friis

Thank you Jia for the quick and detailed reply. If we are breaking down each input species to basis species and aggregating the unique basis species is there a need to use free or should we always be using it? This is still a bit unclear to me as it would seem that the bulk specification of sodium bearing species would be sufficient--makes no sense to me that a bulk specification of the sodium ion would include all sodium in other species...seems like double counting? Perhaps two small examples (one with free and one w/o) would help.

I've read the section in one of the manuals regarding this but as a software engineer and not a chemist I'm still a bit unclear. When setting up a basis, we take the set of input species and drill down to get an aggregated set of basis species and then prorate the specified amounts for each species across its subspecies. In this scenario is there a reason to use "free?" Can anyone explain the use of "free" in layman's terms so a software engineer can understand too? LOL

Our application has a series of unit ops that does a mass balance using GWB. A unit op can have one or more species as defined in the currently loaded tdat file (data command). In setting up the basis for the unit op we determine the basis-species for each input species and prorate the amounts. After running the go command we notice that some of the resultant species are not defined in the current tdat. This is a problem as the outputs to a given unit op will be used as inputs to add'l unit ops. Is it normal for some resultant species not to be defined in the current universe of species. Thoughts on how to handle this? Are we forced to have our users ensure that all resultant species are defined (manually?). Thanks for any insight into the most effective way to handle this. P.S. is breaking the input species down into the component basis-species to set up the basis the correct approach?

Here are a few general GWB questions. 1. When GWB is loaded is the default database thermo.tdat if no other database is specified? 2. Can only a single database (tdat) file be loaded at one time? 3. When a tdat file is loaded is that the entire universe of elements, basis species, species that GWB is aware of? 4. When specifying the "inputs" to a reaction before the Go command is executed, will the inputs only consist of basis species? Or can they be gasses, minerals, oxides, etc too (i.e. any non-basis species)? In talking to a colleague we speculated that aqueous species could also be inputs (e.g. copper cyanide) but the swap command (which I have not looked at yet) would need to be used. Is this the case? It seems like several constraints (e.g. pH can also be entered) at this stage as well. 5. If an input to a unit operation in our application contains component(s) that are not known by GWB (i.e., not in the tdat) file is that a viable scenario? I'm a software engineer, not a chemist so sorry if this is a stupid question, but I guess what I'm asking is what is specified in the tdat file a hard constraint? 6. Regarding the resultant species from the reaction (after the Go command is issued) will all of these species be defined in the currently loaded tdat file or can we get resultant species from the reaction that are not defined in the file? Thanks for any insight.