pH of rainwater and of rainwater interacting with limestone

Step 1 - Rainwater

TITLE Calculation of the pH of rain water

RUNTIME
database ../../CrunchDatabase_ThermoChimie_v12a.dbs
speciate_only true
END

PRIMARY_SPECIES
H2O
H+
CO2
END

SECONDARY_SPECIES   
OH- 
HCO3-
CO3-2                                                      
END

GASES
CO2(g)
END

Condition Rainwater
units            mol/kgw
temperature      15
pH               charge 
CO2              CO2(g) 410e-6 ! atm
END

Step 2 - Rainwater equilibrates with calcite

TITLE Equilibrium of rain water with limestone and atmospheric CO2(g)

RUNTIME
database ../../CrunchDatabase_ThermoChimie_v12a.dbs
speciate_only true
END

PRIMARY_SPECIES
H2O
H+
CO2
Ca+2
END

SECONDARY_SPECIES   
OH- 
HCO3-
CO3-2  
Ca(HCO3)+                                                    
END

GASES
CO2(g)
END

MINERALS
Calcite
END


Condition Rainwater
units            mol/kgw
temperature      15.0
pH               charge 
CO2              CO2(g) 410e-6 ! atm
Ca+2             Calcite       ! Default Saturation index is 0 
Calcite          0 specific_surface_area 10 threshold 1e-6
END