Model III Data

The System

The sources of data used to determine mixture parameters W, Q and U in the activity coefficient equations for this ternary (3 ion) system are listed in Table 8 of Clegg et al. (1998b). Fits of the model are described in section 3.10 of that paper. The following types of data were considered:

Solubilities of the solid NH4Cl(s) in the ternary solutions.
Mean activity coefficients of HCl from electromotive force measurements.
The activity coefficient ratio of the ions NH4⁺ and H⁺, from measurements of the stoichiometric acid dissociation constant of NH4⁺ (used for comparison only).

References: S. L. Clegg, P. Brimblecombe and A. S. Wexler (1998b) J. Phys. Chem. A 102, 2155-2171.

Weights

The values listed in the tables below are based upon those used in the fits of the model. However, they have been normalised for each type of measurement so that the maximum weight for a data point in each table is always unity. Points given zero weight are those which either appear to be in error, or are used for comparison only (and were not fitted). Points with a weight of "-" are outside the temperature or concentration limits of the current model, and have not been assessed for accuracy.

The Data

The experimental data used to fit the activity coefficient model are listed in the tables below. Notes at the end of each one define the tabulated quantities, and identify the sources of the measurements.

(1) Solubilities of Solid Phases

  mHCl     mNH4Cl      t    solid    ref.       weight    pHCl
  0.000    5.5527     0.0     1     a(945)        -        -     
  4.595    1.9032     0.0     1     a(945)        -        -     
  5.963    1.2915     0.0     1     a(945)        -        -     
  7.501    0.8916     0.0     1     a(945)        -        -     
  8.503    0.7081     0.0     1     a(945)        -        -      
 10.622    0.5861     0.0     1     a(945)        -        -     
 13.484    0.5691     0.0     1     a(945)        -        -      
 14.442    0.5854     0.0     1     a(945)        -        -     
 16.557    0.6869     0.0     1     a(945)        -        -     
 16.943    0.7183     0.0     1     a(945)        -        -     
 18.854    0.8255     0.0     1     a(945)        -        -     
 21.357    1.0815     0.0     1     a(945)        -        -     
 24.078    1.5277     0.0     1     a(945)        -        -     
  1.736    3.7863     0.0     1     a(946)        -        -     
  3.472    2.6031     0.0     1     a(946)        -        -     
  5.308    1.8092     0.0     1     a(946)        -        -     
  7.363    1.3802     0.0     1     a(946)        -        -     
 12.281    0.8371     0.0     1     a(946)        -        -     
 22.300    1.0483     0.0     1     a(946)        -        -     
  1.828    4.9853    25.0     1     a(946)       0.0       -     
  3.609    3.4438    25.0     1     a(946)       0.0       -     
  5.522    2.6348    25.0     1     a(946)       0.0       -     
  7.566    1.9339    25.0     1     a(946)       1.0       -     
 12.562    1.2844    25.0     1     a(946)       1.0       -     
 19.290    1.4447    25.0     1     a(946)       0.0       -     
  2.002    7.2323    50.0     1     a(946)        -        -     
  3.946    5.5143    50.0     1     a(946)        -        -     
  5.835    3.8450    50.0     1     a(946)        -        -     
  7.950    2.9803    50.0     1     a(946)        -        -     
 13.060    2.0772    50.0     1     a(946)        -        -     
 16.348    1.9994    50.0     1     a(946)        -        -     
  2.160    9.2738    80.0     1     a(946)        -        -     
  4.219    7.1903    80.0     1     a(946)        -        -     
  6.428    6.1342    80.0     1     a(946)        -        -     
  8.638    4.8577    80.0     1     a(946)        -        -     
 12.368    3.5317    80.0     1     a(946)        -        -     
  2.324   11.4070   100.0     1     a(946)        -        -     
  4.649    9.8227   100.0     1     a(946)        -        -     
  6.857    7.7895   100.0     1     a(946)        -        -     
  9.353    6.8053   100.0     1     a(946)        -        -     
 15.903    0.8289    25.0     1     a(947)       0.0      53.000 
 14.956    0.8322    25.0     1     a(947)       0.0      87.400 
 11.518    0.9059    25.0     1     a(947)       0.0      10.500 
  9.448    0.9386    25.0     1     a(947)       1.0      2.100  
  0.000    5.5438     0.0     1     a(939)        -        -     
  0.348    5.2361     0.0     1     a(939)        -        -     
  0.656    4.8921     0.0     1     a(939)        -        -     
  1.283    4.3082     0.0     1     a(939)        -        -     
  2.482    3.1784     0.0     1     a(939)        -        -     
  6.142    1.2617     0.0     1     a(939)        -        -     
  7.150    1.0312     0.0     1     a(939)        -        -     
  5.000    3.2566    25.0     1     a(940)       0.0       -     
  1.001    6.3768    25.0     1     a(940)       1.0       -     
  0.499    6.8890    25.0     1     a(940)       1.0       -     
  0.250    7.1956    25.0     1     a(940)       1.0       -     
  0.000    7.4125    25.0     1     a(940)       1.0       -     
  0.000    7.3788    25.0     1     a(941)       1.0       -     
  0.252    7.1204    25.0     1     a(941)       1.0       -     
  0.497    6.8272    25.0     1     a(941)       1.0       -     
  1.001    6.3219    25.0     1     a(941)       1.0       -     
  5.004    2.8162    25.0     1     a(941)       1.0       -     
 18.892    1.2721    25.0     1     a(942)       1.0       -     
 15.047    1.0213    25.0     1     a(942)       0.0       -     
 11.744    1.0436    25.0     1     a(942)       0.0       -     
  9.125    1.3145    25.0     1     a(942)       1.0       -     
  7.749    1.6376    25.0     1     a(942)       1.0       -     
  6.928    1.9054    25.0     1     a(942)       1.0       -     
  5.562    2.5435    25.0     1     a(942)       1.0       -     
  4.728    3.0437    25.0     1     a(942)       1.0       -     
  4.347    3.3042    25.0     1     a(942)       1.0       -     
  3.802    3.6965    25.0     1     a(942)       1.0       -     
  2.573    4.7332    25.0     1     a(942)       1.0       -     
  2.312    4.9805    25.0     1     a(942)       1.0       -     
  2.136    5.1626    25.0     1     a(942)       1.0       -        
  1.305    5.9892    25.0     1     a(942)       1.0       -        
  0.555    6.7738    25.0     1     a(942)       1.0       -        
  0.000    7.4057    25.0     1     a(942)       1.0       -        
  8.599    0.0642   -91.0     3     a(943)       1.0       -        
  8.599    0.0642   -91.0     1     a(943)        -        -        
  8.599    0.0642   -91.0     0     a(943)        -        -        
  7.407    0.1261   -75.0     1     a(943)        -        -        
  7.407    0.1261   -75.0     0     a(943)        -        -        
  3.973    0.7103   -27.9     1     a(943)        -        -        
  3.973    0.7103   -27.9     0     a(943)        -        -        
  3.059    0.9523   -20.3     1     a(943)        -        -        
  3.059    0.9523   -20.3     0     a(943)        -        -        
  0.656    2.9685   -18.6     1     a(943)        -        -        
  0.656    2.9685   -18.6     0     a(943)        -        -        
 13.239    0.0964     0.0     1     a(943)        -        -        
 12.166    0.1764     0.0     1     a(943)        -        -        
 10.049    0.3361     0.0     1     a(943)        -        -        
  8.737    0.5181     0.0     1     a(943)        -        -        
  6.738    1.0186     0.0     1     a(943)        -        -        
  4.323    2.0098     0.0     1     a(943)        -        -        
  3.094    2.6716     0.0     1     a(943)        -        -        
  1.820    3.5298     0.0     1     a(943)        -        -        
  1.074    4.0763     0.0     1     a(943)        -        -        
  0.345    4.6858     0.0     1     a(943)        -        -        
  0.000    5.0044     0.0     1     a(943)        -        -        
 14.169    0.1187    25.0     1     a(943)       0.0       -        
 11.415    0.6214    25.0     1     a(943)       0.0       -        
 11.182    0.2275    25.0     1     a(943)       0.0       -        
  7.656    1.6595    25.0     1     a(943)       0.0       -        
  4.927    2.7287    25.0     1     a(943)       0.0       -        
  2.178    4.7245    25.0     1     a(943)       0.0       -        
  1.092    5.4683    25.0     1     a(943)       0.0       -        
  0.707    5.8257    25.0     1     a(943)       0.0       -        
  0.310    6.2021    25.0     1     a(943)       0.0       -        
  0.000    6.4914    25.0     1     a(943)       0.0       -        
  4.721    5.0670    50.0     1     a(943)        -        -        
  2.478    6.3786    50.0     1     a(943)        -        -        
  1.381    7.0241    50.0     1     a(943)        -        -        
  0.586    7.5696    50.0     1     a(943)        -        -        
  0.000    8.0533    50.0     1     a(943)        -        -        
  3.188    7.8680    75.0     1     a(943)        -        -        
  1.767    8.6417    75.0     1     a(943)        -        -        
  0.661    9.2656    75.0     1     a(943)        -        -      
  0.000    9.6577    75.0     1     a(943)        -        -      
  9.197    0.6278    25.0     1     a(944)       0.0     760.0    
  6.355    0.5745    25.0     1     a(944)       0.0       -      
  3.706    1.0545    25.0     1     a(944)       0.0       -      
  0.877    2.8488    25.0     1     a(944)       0.0       -

Notes and References

Prefix m denotes molality; t - experimental temperature (^oC); solid - identity of the solid which the solution is saturated with respect to; ref. - source of data; weight - the weight given to the data point in the fit of the model (normalised); pHCl - the equilibrium partial pressure of HCl (mm Hg).
Solids: 0 = ice, 1 = NH4Cl(s).
Sources: a - H. L. Silcock, Solubilities of Inorganic and Organic Compounds, Vol. 3, Pergamon, Oxford, 1979, (the table numbers are given in parentheses).

(2) Mean Activity Coefficients of HCl

  mHCl     mNH4Cl      t    gamma    ref.      weight    
  0.02500  0.00000   25.0   0.8654     b         1.0     
  0.02168  0.00333   25.0   0.8645     b         1.0     
  0.01732  0.00768   25.0   0.8631     b         1.0     
  0.01289  0.01211   25.0   0.8621     b         1.0     
  0.00805  0.01695   25.0   0.8608     b         1.0     
  0.00258  0.02243   25.0   0.8592     b         1.0     
  0.05000  0.00000   25.0   0.8310     b         1.0     
  0.04494  0.00506   25.0   0.8286     b         1.0     
  0.03465  0.01535   25.0   0.8275     b         1.0     
  0.02632  0.02368   25.0   0.8265     b         1.0     
  0.01709  0.03291   25.0   0.8242     b         1.0     
  0.00578  0.04422   25.0   0.8227     b         1.0     
  0.05000  0.00000   25.0   0.8308     b         1.0     
  0.04461  0.00539   25.0   0.8294     b         1.0     
  0.04094  0.00907   25.0   0.8286     b         1.0     
  0.03202  0.01798   25.0   0.8295     b         1.0     
  0.02064  0.02936   25.0   0.8254     b         1.0     
  0.01151  0.03849   25.0   0.8240     b         1.0     
  0.10000  0.00000   25.0   0.7963     b         1.0     
  0.08922  0.01078   25.0   0.7947     b         1.0     
  0.06424  0.03576   25.0   0.7906     b         1.0     
  0.04919  0.05081   25.0   0.7883     b         1.0     
  0.03019  0.06981   25.0   0.7853     b         1.0     
  0.01038  0.08962   25.0   0.7818     b         1.0     
  0.10000  0.00000   25.0   0.7967     b         1.0     
  0.08658  0.01342   25.0   0.7941     b         1.0     
  0.08130  0.01870   25.0   0.7929     b         1.0     
  0.05886  0.04114   25.0   0.7894     b         1.0     
  0.04172  0.05828   25.0   0.7870     b         1.0     
  0.01942  0.08058   25.0   0.7831     b         1.0     
  0.25000  0.00000   25.0   0.7601     b         1.0     
  0.21835  0.03165   25.0   0.7561     b         1.0     
  0.17160  0.07840   25.0   0.7498     b         1.0     
  0.13043  0.11957   25.0   0.7437     b         1.0     
  0.09195  0.15805   25.0   0.7385     b         1.0     
  0.02465  0.22535   25.0   0.7305     b         1.0     
  0.50000  0.00000   25.0   0.7572     b         1.0    
  0.46515  0.03485   25.0   0.7521     b         1.0    
  0.39840  0.10160   25.0   0.7451     b         1.0    
  0.29540  0.20460   25.0   0.7324     b         1.0    
  0.20925  0.29075   25.0   0.7215     b         1.0    
  0.10155  0.39845   25.0   0.7086     b         1.0    
  1.00000  0.00000   25.0   0.8100     b         1.0    
  0.88220  0.11780   25.0   0.7930     b         1.0    
  0.78020  0.21980   25.0   0.7805     b         1.0    
  0.60550  0.39450   25.0   0.7600     b         1.0    
  0.41720  0.58280   25.0   0.7379     b         1.0    
  0.20640  0.79360   25.0   0.7128     b         1.0    
  1.00000  0.00000   25.0   0.8092     b         1.0    
  0.89200  0.10800   25.0   0.7962     b         1.0    
  0.70490  0.29510   25.0   0.7699     b         1.0    
  0.50650  0.49350   25.0   0.7475     b         1.0    
  0.33060  0.66940   25.0   0.7277     b         1.0    
  0.11530  0.88470   25.0   0.7022     b         1.0    
  2.00000  0.00000   25.0   1.0086     b         1.0    
  1.59580  0.40420   25.0   0.9461     b         1.0    
  1.36300  0.63700   25.0   0.9107     b         1.0    
  0.97380  1.02620   25.0   0.8596     b         1.0    
  0.68880  1.31120   25.0   0.8208     b         1.0    
  0.18780  1.81220   25.0   0.7605     b         1.0    
  3.00000  0.00000   25.0   1.3159     b         1.0    
  2.79600  0.20400   25.0   1.2721     b         1.0    
  2.39790  0.60210   25.0   1.1866     b         1.0    
  1.81830  1.18170   25.0   1.0716     b         1.0    
  1.22340  1.77660   25.0   0.9751     b         1.0    
  0.66960  2.33040   25.0   0.8846     b         1.0    
  0.99992  0.00000   25.0   0.8113     c         1.0    
  0.85838  0.14158   25.0   0.7950     c         1.0    
  0.63545  0.36458   25.0   0.7695     c         1.0    
  0.40046  0.59965   25.0   0.7442     c         1.0    
  0.22833  0.77183   25.0   0.7268     c         1.0    
  0.10752  0.89268   25.0   0.7148     c         1.0    
  0.10000  0.00000   25.0   0.7965     d         1.0    
  0.09000  0.01000   25.0   0.7952     d         1.0    
  0.07000  0.03000   25.0   0.7912     d         1.0    
  0.05000  0.05000   25.0   0.7884     d         1.0    
  0.03000  0.07000   25.0   0.7860     d         1.0    
  0.01000  0.09000   25.0   0.7829     d         1.0    
  0.00000  0.10000   25.0   0.7820     d         1.0    
  0.50000  0.00000   25.0   0.7588     d         1.0    
  0.45000  0.05000   25.0   0.7528     d         1.0    
  0.35000  0.15000   25.0   0.7401     d         1.0    
  0.25000  0.25000   25.0   0.7285     d         1.0    
  0.15000  0.35000   25.0   0.7170     d         1.0    
  0.05000  0.45000   25.0   0.7060     d         1.0    
  0.00000  0.50000   25.0   0.6994     d         1.0    
  1.00000  0.00000   25.0   0.8104     d         1.0    
  0.90000  0.10000   25.0   0.7976     d         1.0    
  0.70000  0.30000   25.0   0.7718     d         1.0    
  0.50000  0.50000   25.0   0.7494     d         1.0    
  0.30000  0.70000   25.0   0.7264     d         1.0    
  0.10000  0.90000   25.0   0.7044     d         1.0    
  0.00000  1.00000   25.0   0.6928     d         1.0    
  2.00000  0.00000   25.0   1.0093     d         1.0    
  1.80000  0.20000   25.0   0.9754     d         1.0    
  1.40000  0.60000   25.0   0.9141     d         1.0    
  1.00000  1.00000   25.0   0.8564     d         1.0    
  0.60000  1.40000   25.0   0.8059     d         1.0    
  0.20000  1.80000   25.0   0.7589     d         1.0    
  0.00000  2.00000   25.0   0.7359     d         1.0    
  3.00000  0.00000   25.0   1.3167     d         1.0    
  2.70000  0.30000   25.0   1.2488     d         1.0    
  2.10000  0.90000   25.0   1.1236     d         1.0    
  1.50000  1.50000   25.0   1.0170     d         1.0    
  0.90000  2.10000   25.0   0.9243     d         1.0    
  0.30000  2.70000   25.0   0.8449     d         1.0    
  0.00000  3.00000   25.0   0.8056     d         1.0    
  0.10000  0.00000   20.0   0.7987     d          -     
  0.09000  0.01000   20.0   0.7978     d          -     
  0.07000  0.03000   20.0   0.7934     d          -     
  0.05000  0.05000   20.0   0.7907     d          -     
  0.03000  0.07000   20.0   0.7883     d          -     
  0.01000  0.09000   20.0   0.7847     d          -     
  0.50000  0.00000   20.0   0.7637     d          -     
  0.45000  0.05000   20.0   0.7575     d          -     
  0.35000  0.15000   20.0   0.7444     d          -     
  0.25000  0.25000   20.0   0.7321     d          -     
  0.15000  0.35000   20.0   0.7208     d          -     
  0.05000  0.45000   20.0   0.7089     d          -     
  1.00000  0.00000   20.0   0.8183     d          -     
  0.90000  0.10000   20.0   0.8045     d          -     
  0.70000  0.30000   20.0   0.7780     d          -     
  0.50000  0.50000   20.0   0.7547     d          -     
  0.30000  0.70000   20.0   0.7315     d          -     
  0.10000  0.90000   20.0   0.7091     d          -     
  2.00000  0.00000   20.0   1.0252     d          -     
  1.80000  0.20000   20.0   0.9895     d          -     
  1.40000  0.60000   20.0   0.9262     d          -     
  1.00000  1.00000   20.0   0.8646     d          -     
  0.60000  1.40000   20.0   0.8141     d          -     
  0.20000  1.80000   20.0   0.7656     d          -     
  3.00000  0.00000   20.0   1.3449     d          -     
  2.70000  0.30000   20.0   1.2735     d          -     
  2.10000  0.90000   20.0   1.1434     d          -     
  1.50000  1.50000   20.0   1.0320     d          -     
  0.90000  2.10000   20.0   0.9352     d          -     
  0.30000  2.70000   20.0   0.8535     d          -     
  0.10000  0.00000   30.0   0.7940     d          -     
  0.09000  0.01000   30.0   0.7921     d          -     
  0.07000  0.03000   30.0   0.7889     d          -     
  0.05000  0.05000   30.0   0.7858     d          -     
  0.03000  0.07000   30.0   0.7842     d          -     
  0.01000  0.09000   30.0   0.7807     d          -     
  0.50000  0.00000   30.0   0.7528     d          -     
  0.45000  0.05000   30.0   0.7475     d          -     
  0.35000  0.15000   30.0   0.7349     d          -     
  0.25000  0.25000   30.0   0.7239     d          -     
  0.15000  0.35000   30.0   0.7127     d          -     
  0.05000  0.45000   30.0   0.7018     d          -     
  1.00000  0.00000   30.0   0.8017     d          -     
  0.90000  0.10000   30.0   0.7896     d          -     
  0.70000  0.30000   30.0   0.7645     d          -     
  0.50000  0.50000   30.0   0.7427     d          -     
  0.30000  0.70000   30.0   0.7206     d          -     
  0.10000  0.90000   30.0   0.6992     d          -     
  2.00000  0.00000   30.0   0.9929     d          -     
  1.80000  0.20000   30.0   0.9598     d          -     
  1.40000  0.60000   30.0   0.9003     d          -     
  1.00000  1.00000   30.0   0.8463     d          -     
  0.60000  1.40000   30.0   0.7973     d          -     
  0.20000  1.80000   30.0   0.7523     d          -     
  3.00000  0.00000   30.0   1.2856     d          -     
  2.70000  0.30000   30.0   1.2215     d          -     
  2.10000  0.90000   30.0   1.1023     d          -     
  1.50000  1.50000   30.0   1.0007     d          -     
  0.90000  2.10000   30.0   0.9105     d          -     
  0.30000  2.70000   30.0   0.8350     d          -     
  0.10000  0.00000   35.0   0.7910     d          -     
  0.09000  0.01000   35.0   0.7900     d          -     
  0.07000  0.03000   35.0   0.7860     d          -     
  0.05000  0.05000   35.0   0.7832     d          -     
  0.03000  0.07000   35.0   0.7814     d          -     
  0.01000  0.09000   35.0   0.7786     d          -     
  0.50000  0.00000   35.0   0.7477     d          -     
  0.45000  0.05000   35.0   0.7423     d          -     
  0.35000  0.15000   35.0   0.7321     d          -     
  0.25000  0.25000   35.0   0.7196     d          -     
  0.15000  0.35000   35.0   0.7089     d          -     
  0.05000  0.45000   35.0   0.6981     d          -     
  1.00000  0.00000   35.0   0.7940     d          -     
  0.90000  0.10000   35.0   0.7822     d          -     
  0.70000  0.30000   35.0   0.7577     d          -     
  0.50000  0.50000   35.0   0.7362     d          -     
  0.30000  0.70000   35.0   0.7148     d          -     
  0.10000  0.90000   35.0   0.6947     d          -     
  2.00000  0.00000   35.0   0.9775     d          -     
  1.80000  0.20000   35.0   0.9460     d          -     
  1.40000  0.60000   35.0   0.8886     d          -     
  1.00000  1.00000   35.0   0.8366     d          -     
  0.60000  1.40000   35.0   0.7896     d          -     
  0.20000  1.80000   35.0   0.7459     d          -

Notes and References

Prefix m denotes molality; t - experimental temperature (^oC); gamma - mean molal activity coefficient of HCl; ref. - source of data; weight - the weight given to the data point in the fit of the model (normalised).
Sources: b - R. A. Robinson, R. N. Roy and R. G. Bates (1974) J. Soln. Chem. 3, 837-846; c - C. Y. Chan, K. H. Khoo and T. K. Lim (1979) J. Soln. Chem. 8, 41-52; d - C. J. Downes (1975) J. Chem. Soc., Faraday Trans. 1, 425-434.

(3) The Activity Coefficient Ratio f [NH4]/f [H]

  mHCl     mNH4Cl      t    ratio     ref.     weight                       
  0.0      0.512     25.0   0.918      e         0.0     
  0.0      1.054     25.0   0.778      e         0.0     
  0.0      1.611     25.0   0.675      e         0.0     
  0.0      2.201     25.0   0.612      e         0.0     
  0.0      2.821     25.0   0.543      e         0.0     
  0.0      3.475     25.0   0.493      e         0.0     
  0.0      4.162     25.0   0.457      e         0.0     
  0.0      4.358     25.0   0.436      e         0.0     
  0.0      4.887     25.0   0.405      e         0.0     
  0.0      5.670     25.0   0.359      e         0.0     
  0.0      6.480     25.0   0.318      e         0.0

Notes and References

Prefix m denotes molality; t - the experimental temperature (^oC); ratio - value of f [NH4]/f [H], where f is the mole fraction activity coefficient of the ion for a reference state of infinite dilution in water (see also note below); ref. - source of data; weight - the weight given to the data point in the fit of the model (normalised).
The stoichiometric acid dissociation constants measured by Maeda and Kato (1995) are equivalent to Ka x g[NH4]/(g[H] x g[NH3]), where Ka is the thermodynamic acid dissociation constant of NH4⁺, and g is the molal activity coefficient of the ion. Using Ka equal to 5.6937E-10 mol kg^-1, and taking values of g[NH3] in aqueous NH4Cl also determined by Maeda and Kato, the ratio of the two cation activity coefficients was obtained from the stoichiometric dissociation constant. Values of the ratio (listed in the table) are the same on both the mole fraction and molality scales.
These data were used for comparison only, and were not included in the fit of the activity coefficient model parameters.
Source: e - M. Maeda, H. Furuhashi and J. Ikami (1993) J. Chem. Soc., Faraday Trans. 89, 3371-3374.

Model III: Data for Aqueous H+ - NH4+ - Cl−

The System

Weights

The Data

(1) Solubilities of Solid Phases

(2) Mean Activity Coefficients of HCl

(3) The Activity Coefficient Ratio f [NH4]/f [H]

Model III: Data for Aqueous H⁺ - NH₄⁺ - Cl⁻