Of course, it depends upon what metals one is most concerned about. A general formula, analogous to the Langelier Index, is what can be called a saturation index (SI), or SI = log10(Q/Ksp) in which Q = the ion activity productKsp = the solubility constant for the given temperature The interpretation is as follows, again similar to Langelier Index for CaCO3 saturation: SI> 0 = supersaturation SI = 0 = saturation equilibrium SI < 0 = undersaturation. Concentrations, in most aqueous solutions with reasonable ionic strength, can be substituted for activities. Hope this helps!

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Of course, it depends upon what metals one is most concerned about. A general formula, analogous to the Langelier Index, is what can be called a saturation index (SI), or
SI = log10(Q/Ksp) in which
Q = the ion activity productKsp = the solubility constant for the given temperature
The interpretation is as follows, again similar to Langelier Index for CaCO3 saturation:
SI> 0 = supersaturation
SI = 0 = saturation equilibrium
SI < 0 = undersaturation.
Concentrations, in most aqueous solutions with reasonable ionic strength, can be substituted for activities.
Hope this helps!