Questions about Vm Under SOLUTION_SPECIES

[TRJ]

Going through the manual, I realized that for Vm, normally we input a series of parameters into PHREEQC to calculate the specific volume of aqueous species. However, I also spotted once there was only one value input for Vm. I'm wondering if this is the specific volume or if I'm wrong, what does this single value mean?

[dlparkhurst]

You'll have to look at the documentation for SOLUTION_SPECIES to see the formula used for calculating molar volume. You can find the documentation either through the Help button in PhreeqcI, or in the file phreeqc3.chm for the latest batch version, normally installed in C:\Program Files\USGS\phreeqc-3.8.2-16969-x64\doc.