Dear Sir, I have noticed something interesting whilst using PHREEQC for copper speciation modeling. I have noticed that the llnl.dat database has provided different stability constants for the various copper acetate complexes to the Minteq database (please see the table below): Cu Acetate Log_k llnl.dat 1 1 2.525 1 2 5.882 1 3 9.379 1 4 - Minteq.dat 1 1 2.22 1 2 3.63 1 3 3.1 1 4 2.9 The constants shown above, especially the ones displayed in llnl.dat, are significantly higher than the literature values. Since the quality of the speciation model predictions is solely dependant on the stability constants used, the discrepancies between the logK values may result in confusion and inaccurate predictions of the speicies distribution. Could you please comment on the situation and could you please also tell me what the sources of the constants listed in llnl.dat and Minteq.dat are? Thanks in advance for your help! Yours sincerely, Zhi Ling ZENG
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