Concentrated LiCl solution using Pitzer database, strange results for pH

[KHeppner]

Hello,

I came across this solution where you add LiCl at a high concentration (near LiCl saturation).  The results are strange in that the activity coefficients calculated for H+ and Li+ are very high.  Thus, low pH is predicted, which is incorrect.  See example input file below showing this behaviour.

DATABASE c:\phreeqc\database\pitzer.dat
SOLUTION 1
 units mol/kgw
 temp 80
 press 1
Cl 20
 Li 20
 pH 7 charge
 END

[dlparkhurst]

First, it is not possible to measure a single-ion activity coefficient.

Sorry, but it is not surprising that activities are unreliable in a very concentrated solutions.

[KHeppner]

Thanks David,

I just wanted to point it out.  Perhaps it was obvious :).  Appreciate the feedback.

kind regards,
Kevin