# phreeqc-2 v2.7 molarity/molality conversion oddity

Below is the output of my simulation. I defined a solution with 0.3 mmol/l phosphate. Phreeqc converts this into a molality of 3.001e-04. The mass of water is reported as 1.000e+00 so the conversion to molality should be 3.000e-04 instead of 3.001e-04.

```------------------------------------
Reading input data for simulation 1.
------------------------------------```

```        SOLUTION 1
units mmol/L
Ca              2
Mg              2
Cl              8
K               0.5
N(+5)           0.5
Na              0.3
P(+5)           0.3
end
-------------------------------------------
Beginning of initial solution calculations.
-------------------------------------------```

Initial solution 1.

-----------------------------Solution composition------------------------------

Elements Molality Moles

```        Ca                2.001e-03   2.001e-03
Cl                8.004e-03   8.004e-03
K                 5.002e-04   5.002e-04
Mg                2.001e-03   2.001e-03
N(5)              5.002e-04   5.002e-04
Na                3.001e-04   3.001e-04
P(5)              3.001e-04   3.001e-04```

----------------------------Description of solution----------------------------

```                                       pH  =   7.000
pe  =   4.000
Activity of water  =   1.000
Ionic strength  =   1.266e-02
Mass of water (kg)  =   1.000e+00
Total alkalinity (eq/kg)  =   4.950e-04
Total carbon (mol/kg)  =   0.000e+00
Total CO2 (mol/kg)  =   0.000e+00
Temperature (deg C)  =  25.000
Electrical balance (eq)  =  -1.949e-04
Percent error, 100*(Cat-|An|)/(Cat+|An|)  =  -1.12
Iterations  =   4
Total H  = 1.110511e+02
Total O  = 5.552803e+01```

----------------------------Distribution of species----------------------------

```                                                   Log       Log         Log
Species            Molality    Activity  Molality  Activity     Gamma```

```        H+                1.103e-07   1.000e-07    -6.957    -7.000    -0.043
OH-               1.082e-07   9.633e-08    -6.966    -7.016    -0.050
H2O               5.553e+01   9.998e-01     1.744    -0.000     0.000
Ca               2.001e-03
Ca+2              1.955e-03   1.268e-03    -2.709    -2.897    -0.188
CaHPO4            3.966e-05   3.966e-05    -4.402    -4.402     0.000
CaNO3+            3.148e-06   2.808e-06    -5.502    -5.552    -0.050
CaCl+             2.141e-06   1.910e-06    -5.669    -5.719    -0.050
CaPO4-            1.112e-06   9.921e-07    -5.954    -6.003    -0.050
CaCl2             1.595e-08   1.595e-08    -7.797    -7.797     0.000
CaP2O7-2          7.366e-09   4.648e-09    -8.133    -8.333    -0.200
CaOH+             2.008e-09   1.791e-09    -8.697    -8.747    -0.050
CaH2PO4+          2.032e-13   1.813e-13   -12.692   -12.742    -0.050
Cl(-1)           8.004e-03
Cl-               7.993e-03   7.103e-03    -2.097    -2.149    -0.051
MgCl+             7.988e-06   7.126e-06    -5.098    -5.147    -0.050
CaCl+             2.141e-06   1.910e-06    -5.669    -5.719    -0.050
NaCl              3.337e-07   3.337e-07    -6.477    -6.477     0.000
KCl               1.060e-07   1.060e-07    -6.975    -6.975     0.000
CaCl2             1.595e-08   1.595e-08    -7.797    -7.797     0.000
HCl               1.595e-10   1.595e-10    -9.797    -9.797     0.000
Cl(1)            2.671e-38
HClO              2.051e-38   2.051e-38   -37.688   -37.688     0.000
ClO-              6.201e-39   5.532e-39   -38.208   -38.257    -0.050
Cl(3)            0.000e+00
ClO2-             0.000e+00   0.000e+00   -67.211   -67.260    -0.050
HClO2             0.000e+00   0.000e+00   -71.091   -71.091     0.000
Cl(5)            0.000e+00
ClO3-             0.000e+00   0.000e+00   -82.361   -82.411    -0.050
Cl(7)            0.000e+00
ClO4-             0.000e+00   0.000e+00  -101.814  -101.864    -0.050
H(0)             1.582e-25
H2                7.911e-26   7.935e-26   -25.102   -25.100     0.001
K                5.002e-04
K+                5.000e-04   4.443e-04    -3.301    -3.352    -0.051
KHPO4-            1.707e-07   1.523e-07    -6.768    -6.817    -0.050
KCl               1.060e-07   1.060e-07    -6.975    -6.975     0.000
KOH               1.540e-11   1.540e-11   -10.812   -10.812     0.000
KP2O7-3           1.731e-13   6.134e-14   -12.762   -13.212    -0.451
Mg               2.001e-03
Mg+2              1.932e-03   1.285e-03    -2.714    -2.891    -0.177
MgHPO4            5.943e-05   5.943e-05    -4.226    -4.226     0.000
MgCl+             7.988e-06   7.126e-06    -5.098    -5.147    -0.050
MgPO4-            1.516e-06   1.353e-06    -5.819    -5.869    -0.050
MgP2O7-2          2.210e-08   1.394e-08    -7.656    -7.856    -0.200
MgH2PO4+          3.746e-13   3.342e-13   -12.426   -12.476    -0.050
Mg4(OH)4+4        2.817e-23   4.844e-24   -22.550   -23.315    -0.765
N(5)             5.002e-04
NO3-              4.971e-04   4.417e-04    -3.304    -3.355    -0.051
CaNO3+            3.148e-06   2.808e-06    -5.502    -5.552    -0.050
HNO3              2.310e-12   2.310e-12   -11.636   -11.636     0.000
Na               3.001e-04
Na+               2.997e-04   2.673e-04    -3.523    -3.573    -0.050
NaCl              3.337e-07   3.337e-07    -6.477    -6.477     0.000
NaHPO4-           1.418e-07   1.265e-07    -6.848    -6.898    -0.050
NaOH              4.442e-12   4.442e-12   -11.352   -11.352     0.000
NaHP2O7-2         9.707e-13   6.125e-13   -12.013   -12.213    -0.200
NaP2O7-3          8.543e-14   3.027e-14   -13.068   -13.519    -0.451
Na2P2O7-2         1.019e-15   6.428e-16   -14.992   -15.192    -0.200
O(0)             0.000e+00
O2                0.000e+00   0.000e+00   -41.997   -41.995     0.001
P(5)             3.001e-04
H2PO4-            1.079e-04   9.622e-05    -3.967    -4.017    -0.050
HPO4-2            9.017e-05   5.690e-05    -4.045    -4.245    -0.200
MgHPO4            5.943e-05   5.943e-05    -4.226    -4.226     0.000
CaHPO4            3.966e-05   3.966e-05    -4.402    -4.402     0.000
MgPO4-            1.516e-06   1.353e-06    -5.819    -5.869    -0.050
CaPO4-            1.112e-06   9.921e-07    -5.954    -6.003    -0.050
KHPO4-            1.707e-07   1.523e-07    -6.768    -6.817    -0.050
NaHPO4-           1.418e-07   1.265e-07    -6.848    -6.898    -0.050
MgP2O7-2          2.210e-08   1.394e-08    -7.656    -7.856    -0.200
CaP2O7-2          7.366e-09   4.648e-09    -8.133    -8.333    -0.200
H3PO4             1.482e-09   1.482e-09    -8.829    -8.829     0.000
PO4-3             7.278e-10   2.579e-10    -9.138    -9.589    -0.451
HP2O7-3           2.896e-10   1.026e-10    -9.538    -9.989    -0.451
H2P2O7-2          6.726e-11   4.244e-11   -10.172   -10.372    -0.200
P2O7-4            3.980e-12   6.286e-13   -11.400   -12.202    -0.801
NaHP2O7-2         9.707e-13   6.125e-13   -12.013   -12.213    -0.200
MgH2PO4+          3.746e-13   3.342e-13   -12.426   -12.476    -0.050
CaH2PO4+          2.032e-13   1.813e-13   -12.692   -12.742    -0.050
KP2O7-3           1.731e-13   6.134e-14   -12.762   -13.212    -0.451
NaP2O7-3          8.543e-14   3.027e-14   -13.068   -13.519    -0.451
H3P2O7-           1.093e-15   9.754e-16   -14.961   -15.011    -0.050
Na2P2O7-2         1.019e-15   6.428e-16   -14.992   -15.192    -0.200
H4P2O7            2.866e-21   2.866e-21   -20.543   -20.543     0.000```

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