# Cl activity-pH plot
SPECIATION
calculationType	"grid"
calculationMethod	1
mainSpecies		Fe
xmin			2
xmax			14
ymin			-2
ymax			0.5
resolution		1000
PLOT
database	c:\phreeqc\database\llnl.dat
xtitle		pH
ytitle		"log {Cl-} activity"
extraText		extratextFe-pH.dat
CHEMISTRY
include 'ht1.inc'   # for a predominance diagram
PHASES
Fix_H+
H+ = H+
	log_k	0.00    # fictive 'phase' : pure phases fix activities
Fix_Cl-
Cl- = Cl-
	log_k	0.00    # fictive 'phase' : pure phases fix activities
SOLUTION 1
	pH        1.8		# lower than min pH
	units     mol/L
   Fe(3)	5e-7                                                 # total Fe
   Na		0.8                                                  # background electrolyte
   Cl		0.8 charge
PHASES 1
FeO(OH)
        FeOOH +3.0000 H+  =  + 1.0000 Fe+++ + 2.0000 H2O
        log_k           0.5345
	-delta_H	-61.9291	kJ/mol	# Calculated enthalpy of reaction	Goethite
#	Enthalpy of formation:	-559.328 kJ/mol
        -analytic -6.0331e+001 -1.0847e-002 4.7759e+003 1.9429e+001 8.1122e+001
#       -Range:  0-200
Fe2O3
        Fe2O3 +6.0000 H+  =  + 2.0000 Fe+++ + 3.0000 H2O
        log_k           0.1086
	-delta_H	-129.415	kJ/mol	# Calculated enthalpy of reaction	Hematite
#	Enthalpy of formation:	-197.72 kcal/mol
        -analytic -2.2015e+002 -6.0290e-002 1.1812e+004 8.0253e+001 1.8438e+002
#       -Range:  0-300
END
# loop here
USE solution 1
EQUILIBRIUM_PHASES 1
Fix_H+ -<x_axis> NaOH 10
	-force_equality true
Fix_Cl-  <y_axis> NaCl 10
	-force_equality true
  FeO(OH)	0	0
  Fe2O3		0	0
END