This keyword data block is used to define a half-reaction and relative log K for each exchange species.
Normally, this data block is included in the database file and only additions and modifications are included
in the input file.
| Keyword |
Explanation |
| Reaction | Association reaction for aqueous species. |
| log K | log K at 25 C for the reaction. Log K must be 0.0 for primary master species. |
| ΔH | Enthalpy of reaction at 25 C for the reaction. |
| Units | Units for ΔH. |
| Gamma (a) | Debye-Huckel a, parameter a in the WATEQ activity-coefficient equation (Truesdell and Jones, 1974). |
| Gamma (b) | Debye-Huckel b, parameter b in the WATEQ activity-coefficient equation (Truesdell and Jones, 1974). |
| Davies | Indicates the Davies equation will be used to calculate an activity coefficient. If -gamma or -davies is not input for an exchange species, the activity of the species is equal to its equivalent fraction. |
Exchange Species
| Reaction |
log K |
ΔH |
Units |
Gamma (a) |
Gamma (b) |
Davies |
Database |
Reference |
Note |
| X- = X- |
0.0 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| Na+ + X- = NaX |
0.0 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| K+ + X- = KX |
0.7 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| Li+ + X- = LiX |
-0.08 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| NH4+ + X- = NH4X |
0.6 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| Ca+2 + 2X- = CaX2 |
0.8 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| Mg+2 + 2X- = MgX2 |
0.6 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| Sr+2 + 2X- = SrX2 |
0.91 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| Ba+2 + 2X- = BaX2 |
0.91 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| Mn+2 + 2X- = MnX2 |
0.52 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| Fe+2 + 2X- = FeX2 |
0.44 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| Cu+2 + 2X- = CuX2 |
0.6 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| Zn+2 + 2X- = ZnX2 |
0.8 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| Cd+2 + 2X- = CdX2 |
0.8 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| Pb+2 + 2X- = PbX2 |
1.05 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| Al+3 + 3X- = AlX3 |
0.41 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
| AlOH+2 + 2X- = AlOHX2 |
0.89 |
0.0 |
kJ/mol |
0.0 |
0.0 |
False |
Phreeqc_default |
Phreeqc |
|
References
| RefID |
Reference |
| Phreeqc |
https://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/index.html |
Databases
| DatabaseID |
Notes |
| Phreeqc_default |
Default database from phreeqc-3.4.0-12927 |
