Model II Data

The System

The sources of data used to determine mixture parameters W, Q and U in the activity coefficient equations for this system are listed in Table 5 of Clegg et al. (1998a). Fits of the model are described in section 3.7 of that paper. The following types of data were considered:

Saturation with respect to the solids (NH4)2SO4(s), (NH4)3H(SO4)2(s), and NH4HSO4(s) in the ternary solutions.
Osmotic coefficients of aqueous (NH4)2SO4 - H2SO4 mixtures from isopiestic measurements.
Osmotic coefficients of aqueous NH4HSO4, and of (NH4)3H(SO4)2, from vapour pressure measurements.
Osmotic coefficients of aqueous NH4HSO4, and of aqueous (NH4)2SO4 - H2SO4 mixtures of various compositions, from electrodynamic balance experiments.
Water actiities of aqueous (NH4)2SO4 - H2SO4 mixtures from isopiestic measurements.
Degrees of dissociation of the HSO4⁻ ion in aqueous NH4HSO4 solutions.

References: S. L. Clegg, P. Brimblecombe and A. S. Wexler (1998a) J. Phys. Chem. A 102, 2137-2154.

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 parameterisation of the AIM model for this system was carried out in two stages, first a fit at 298.15 K to obtain parameter values at that temperature, and then a second fit (using data at all other temperatures) to determine the variation of the parameters with temperature. Both sets of weights are listed in the tables below, for those data used in the fits. Other tables, numbers 7 to 10, contain data that were used for comparison only. Here, the weights are either zero or "-" and are listed in a single column.

All fits were limited to molalities of (NH4)2SO4, and H2SO4, less than 33 mol kg^-1.

The Data

The experimental data 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

   mH2SO4     m(NH4)2SO4    t     solid   ref.     weight(298)   weight(T)
  16.3910      4.6372     25.0      3    a(737)       1.0           0.0   
  14.6778      7.8606     25.0      3    a(737)       1.0           0.0   
  14.6884     11.0944     25.0      3    a(737)       1.0           0.0   
  15.3918     13.9135     25.0      3    a(737)       1.0           0.0   
  15.7012     15.0225     25.0      3    a(737)       1.0           0.0   
  15.6342     15.0642     25.0      3    a(737)       1.0           0.0   
  15.6342     15.0642     25.0      2    a(737)       1.0           0.0   
  13.5531     13.2674     25.0      2    a(737)       1.0           0.0   
  12.0910     12.0532     25.0      2    a(737)       1.0           0.0   
   9.8638     10.3303     25.0      2    a(737)       1.0           0.0   
   8.7288      9.3788     25.0      2    a(737)       1.0           0.0   
   8.0220      8.8805     25.0      2    a(737)       1.0           0.0   
   7.3744      8.4238     25.0      2    a(737)       1.0           0.0   
   5.7114      7.8402     25.0      2    a(737)       1.0           0.0   
   4.1836      7.7348     25.0      2    a(737)       1.0           0.0   
   3.2928      7.4145     25.0      2    a(737)       1.0           0.0   
   2.9196      7.1318     25.0      2    a(737)       0.0           0.0   
   2.9196      7.1318     25.0      1    a(737)       1.0           0.0   
   2.5478      6.7441     25.0      1    a(737)       1.0           0.0   
   1.9851      6.4464     25.0      1    a(737)       1.0           0.0   
   0.8828      5.9918     25.0      1    a(737)       1.0           0.0   
   0.4387      5.9412     25.0      1    a(737)       1.0           0.0   
   0.0000      5.7889     25.0      1    a(737)       1.0           0.0   
  15.5425     14.6250     25.0      2    a(744)       0.0           0.0   
  15.5425     14.6250     25.0      3    a(744)       1.0           0.0   
   0.0000      5.7580     25.0      1    a(744)       1.0           0.0   
 287.9176     51.1054     25.0      4    a(739)        -             -    
 234.6424     40.5264     25.0      4    a(739)        -             -    
 105.0068     23.6554     25.0      4    a(739)        -             -    
 164.6370     64.0113     25.0      4    a(739)        -             -    
 164.6370     64.0113     25.0      3    a(739)        -             -    
 131.6644     48.0069     25.0      3    a(739)        -             -    
  62.6663     18.7710     25.0      3    a(739)        -             -    
  40.2713      9.6477     25.0      3    a(739)        -             -    
  26.8548      5.4930     25.0      3    a(739)       1.0           0.0   
  19.9504      4.3003     25.0      3    a(739)       1.0           0.0   
  17.1897      4.4530     25.0      3    a(739)       1.0           0.0   
  15.4986      5.1129     25.0      3    a(739)       1.0           0.0   
  14.7418      5.9032     25.0      3    a(739)       1.0           0.0   
  14.6648      7.4179     25.0      3    a(739)       1.0           0.0   
 793.6106    110.6919     10.0      4    a(742)        -             -    
 347.0582     46.2805     10.0      4    a(742)        -             -    
 245.0714     30.5363     10.0      4    a(742)        -             -    
 131.6069     13.9324     10.0      4    a(742)        -             -    
  70.0374      8.9379     10.0      4    a(742)        -             -    
  63.4176     10.2682     10.0      4    a(742)        -             -    
  63.9266     12.7377     10.0      4    a(742)        -             -    
 143.8762     52.7092     10.0      3    a(742)        -             -    
 120.5397     42.0835     10.0      3    a(742)        -             -    
  72.5566     21.2899     10.0      3    a(742)        -             -    
  42.6710      9.6815     10.0      3    a(742)        -             -    
  38.0791      7.9401     10.0      3    a(742)        -             -    
  34.3045      6.5316     10.0      3    a(742)        -             -    
  29.3201      5.0546     10.0      3    a(742)       0.0           1.0   
  22.1921      3.3810     10.0      3    a(742)       0.0           1.0   
  17.4932      2.8931     10.0      3    a(742)       0.0           1.0   
  14.7121      3.1353     10.0      3    a(742)       0.0           1.0   
  13.4495      3.3903     10.0      3    a(742)       0.0           1.0   
  12.4523      4.9619     10.0      3    a(742)       0.0           1.0   
  12.0983      6.4416     10.0      3    a(742)       0.0           1.0   
  12.2945      9.2603     10.0      3    a(742)       0.0           1.0   
  12.7019     10.5948     10.0      3    a(742)       0.0           1.0   
  12.7019     10.5948     10.0      2    a(742)       0.0           1.0   
  12.8925     10.8099     10.0      2    a(742)       0.0           1.0   
   9.4003      8.3606     10.0      2    a(742)       0.0           1.0   
   7.0960      6.9354     10.0      2    a(742)       0.0           1.0   
   5.3814      6.3249     10.0      2    a(742)       0.0           1.0   
   3.6890      6.1784     10.0      2    a(742)       0.0           1.0   
   2.3805      6.6113     10.0      2    a(742)       0.0           1.0   
   2.3805      6.6113     10.0      1    a(742)       0.0           1.0   
   1.1942      5.9117     10.0      1    a(742)       0.0           1.0   
   0.0000      5.4803     10.0      1    a(742)       0.0           1.0   
  77.6133     23.8617     20.0      3    a(740)        -             -    
  32.3493      6.8381     20.0      3    a(740)       0.0           1.0   
  21.1688      4.1405     20.0      3    a(740)       0.0           1.0   
  13.9395      6.0353     20.0      3    a(740)       0.0           1.0   
  14.4981      5.3213     20.0      3    a(740)       0.0           1.0   
  13.9012      7.3410     20.0      3    a(740)       0.0           1.0   
  13.9838     12.9430     20.0      2    a(740)       0.0           1.0   
  13.6633     12.5630     20.0      2    a(740)       0.0           1.0   
   9.3549      9.5141     20.0      2    a(740)       0.0           1.0   
   6.0550      7.3930     20.0      2    a(740)       0.0           1.0   
   5.0736      6.9465     20.0      2    a(740)       0.0           1.0   
   4.4322      7.1187     20.0      2    a(740)       0.0           1.0   
   3.2066      7.1743     20.0      1    a(740)       0.0           1.0   
   2.6213      6.9745     20.0      1    a(740)       0.0           1.0   
   1.1177      6.1563     20.0      1    a(740)       0.0           1.0   
   0.0000      5.7326     20.0      1    a(740)       0.0           1.0   
   0.0000      5.7069     20.0      1    a(746)       0.0           1.0   
   2.7387      7.2546     20.0      1    a(746)       0.0           1.0   
   2.7387      7.2546     20.0      2    a(746)       0.0           1.0   
   3.8934      6.9400     20.0      2    a(746)       0.0           1.0   
   5.4029      7.1871     20.0      2    a(746)       0.0           1.0   
  14.5646     13.5008     20.0      2    a(746)       0.0           1.0   
  14.5646     13.5008     20.0      3    a(746)       0.0           1.0   
 248.3004    103.7654     20.0      3    a(746)        -             -    
   0.0000      6.0191     30.0      1    a(738)       0.0           0.0   
   2.1975      7.1114     30.0      1    a(738)       0.0           1.0   
   3.1521      7.8162     30.0      1    a(738)       0.0           1.0   
   3.1521      7.8162     30.0      2    a(738)       0.0           1.0   
   3.6330      7.7119     30.0      2    a(738)       0.0           1.0   
   5.2290      7.9562     30.0      2    a(738)       0.0           1.0   
   7.4536      9.0286     30.0      2    a(738)       0.0           1.0   
  11.3294     12.0529     30.0      2    a(738)       0.0           1.0   
  16.6493     16.6351     30.0      2    a(738)       0.0           1.0   
  16.6493     16.6351     30.0      3    a(738)       0.0           1.0   
  15.7215     14.1026     30.0      3    a(738)       0.0           1.0   
  14.9948      9.1262     30.0      3    a(738)       0.0           1.0   
  15.8769      6.8348     30.0      3    a(738)       0.0           1.0   
  17.5197      5.4355     30.0      3    a(738)       0.0           1.0   
  20.4674      4.8612     30.0      3    a(738)       0.0           1.0   
  27.5581      6.0681     30.0      3    a(738)       0.0           1.0   
  34.3783      8.2711     30.0      3    a(738)        -             -    
  90.3323     31.9778     30.0      3    a(738)        -             -    
 792.7768    350.0235     30.0      3    a(738)        -             -    
   0.0000      5.9536     30.0      1    a(741)       0.0           1.0   
   3.1692      8.0220     30.0      2    a(741)       0.0           1.0   
   7.7709      9.4527     30.0      2    a(741)       0.0           1.0   
  16.7049     16.6293     30.0      2    a(741)       0.0           1.0   
  26.1508      5.7702     30.0      3    a(741)       0.0           1.0   
   0.0000      6.3926     30.0      1    a(741)       0.0           0.0   
 421.2508    184.3078     30.0      3    a(742)        -             -    
 211.0200     86.4064     30.0      3    a(742)        -             -    
  80.0683     26.7837     30.0      3    a(742)        -             -    
  48.1683     13.2852     30.0      3    a(742)        -             -    
  35.6963      8.4785     30.0      3    a(742)        -             -    
  27.6460      6.0490     30.0      3    a(742)       0.0           1.0   
  26.1508      5.7702     30.0      3    a(742)       0.0           1.0   
  22.0660      5.4104     30.0      3    a(742)       0.0           1.0   
  20.4415      4.9614     30.0      3    a(742)       0.0           1.0   
  18.4926      4.8753     30.0      3    a(742)       0.0           1.0   
  15.5977      6.7022     30.0      3    a(742)       0.0           1.0   
  15.5139      9.4544     30.0      3    a(742)       0.0           1.0   
  15.2222     11.0470     30.0      3    a(742)       0.0           1.0   
  15.6656     12.9955     30.0      3    a(742)       0.0           1.0   
  16.0605     14.6480     30.0      3    a(742)       0.0           1.0   
  16.7049     16.6293     30.0      3    a(742)       0.0           1.0   
  14.6442     14.9758     30.0      2    a(742)       0.0           1.0   
  10.5146     11.4554     30.0      2    a(742)       0.0           1.0   
   7.7709      9.4527     30.0      2    a(742)       0.0           1.0   
   6.1335      8.5347     30.0      2    a(742)       0.0           1.0   
   4.7335      8.1171     30.0      2    a(742)       0.0           1.0   
   3.7027      7.9200     30.0      2    a(742)       0.0           1.0   
   3.3667      7.8457     30.0      1    a(742)       0.0           1.0   
   3.3667      7.8457     30.0      2    a(742)       0.0           1.0   
   3.1191      7.9661     30.0      1    a(742)       0.0           1.0   
   2.4034      7.2885     30.0      1    a(742)       0.0           1.0   
   1.2738      6.5174     30.0      1    a(742)       0.0           1.0   
   0.0000      5.9536     30.0      1    a(742)       0.0           1.0   
  67.1895     22.2262     40.0      3    a(740)        -             -    
  30.7455      8.2245     40.3      3    a(740)       0.0           0.33  
  19.2047      6.6292     40.3      3    a(740)       0.0           0.33  
  18.3625     11.5651     40.3      3    a(740)       0.0           0.33  
  17.5269     20.3315     40.0      2    a(740)       0.0           0.0   
  13.6250     15.3675     40.3      2    a(740)       0.0           0.33  
   9.4834     11.8549     40.3      2    a(740)       0.0           0.33  
   5.1261      9.3050     40.3      2    a(740)       0.0           0.33  
   3.7977      8.9195     40.3      1    a(740)       0.0           0.33  
   2.5374      7.9866     40.3      1    a(740)       0.0           0.33  
   0.0000      6.2929     40.0      1    a(740)       0.0           0.0   
 113.9502     40.6286      0.0      3    a(740)        -             -    
  30.2153      4.7214      0.0      3    a(740)       0.0           1.0   
  11.9622      2.0120      0.0      3    a(740)       0.0           0.0   
  12.1168      3.5130      0.0      3    a(740)       0.0           1.0   
  12.1753      3.7942      0.0      3    a(740)       0.0           1.0   
  11.2950      4.9548      0.0      3    a(740)       0.0           1.0   
  11.3400      7.5917      0.0      3    a(740)       0.0           1.0   
  12.3814      8.9839      0.0      2    a(740)       0.0           1.0   
  10.8677      8.0900      0.0      2    a(740)       0.0           1.0   
   8.6612      7.5036      0.0      2    a(740)       0.0           0.0   
   5.4724      5.7281      0.0      2    a(740)       0.0           1.0   
   5.0417      5.4705      0.0      2    a(740)       0.0           1.0   
   3.6340      5.6007      0.0      2    a(740)       0.0           1.0   
   2.2130      6.1404      0.0      2    a(740)       0.0           1.0   
   2.2130      6.1404      0.0      1    a(740)       0.0           1.0   
   1.1182      5.6690      0.0      1    a(740)       0.0           1.0   
   0.0000      5.314       0.0      1    a(740)       0.0           1.0   
   4.2106      9.7998     50.0      1    a(741)       0.0           1.0   
   4.2106      9.7998     50.0      2    a(741)       0.0           1.0   
   5.1054      9.7884     50.0      2    a(741)       0.0           1.0   
   8.3919     11.5230     50.0      2    a(741)       0.0           1.0   
  23.8427     26.2539     50.0      2    a(741)       0.0           1.0   
  23.8427     26.2539     50.0      3    a(741)       0.0           1.0   
  27.3722      9.5443     50.0      3    a(741)       0.0           1.0   
 645.7775    301.4616     50.0      3    a(742)        -             -    
 201.3059     89.5350     50.0      3    a(742)        -             -    
 171.6268     73.5333     50.0      3    a(742)        -             -    
  85.7349     33.1847     50.0      3    a(742)        -             -    
  68.3546     25.0463     50.0      3    a(742)        -             -    
  57.1964     19.8601     50.0      3    a(742)        -             -    
  43.1997     14.6584     50.0      3    a(742)        -             -    
  28.4728      9.0636     50.0      3    a(742)       0.0           1.0   
  26.0822      8.7379     50.0      3    a(742)       0.0           1.0   
  23.7994      8.4333     50.0      3    a(742)       0.0           1.0   
  23.3552      8.9740     50.0      3    a(742)       0.0           1.0   
  20.1945     10.1770     50.0      3    a(742)       0.0           1.0   
  19.7080     12.1577     50.0      3    a(742)       0.0           1.0   
  19.9427     14.7648     50.0      3    a(742)       0.0           1.0   
  20.4860     17.8498     50.0      3    a(742)       0.0           1.0   
  21.9617     20.9130     50.0      3    a(742)       0.0           1.0   
  23.5046     25.7447     50.0      3    a(742)       0.0           1.0   
  23.5046     25.7447     50.0      2    a(742)       0.0           1.0   
  12.8479     15.2105     50.0      2    a(742)       0.0           1.0   
   9.8519     12.6199     50.0      2    a(742)       0.0           1.0   
   8.3919     11.5230     50.0      2    a(742)       0.0           1.0   
   6.2999     10.1932     50.0      2    a(742)       0.0           1.0   
   5.5747      9.9235     50.0      2    a(742)       0.0           1.0   
  20.8960     23.0130     50.0      2    a(742)       0.0           1.0   
  15.7930     18.0648     50.0      2    a(742)       0.0           1.0   
  12.9599     15.2660     50.0      2    a(742)       0.0           1.0   
   5.1054      9.7884     50.0      2    a(742)       0.0           1.0   
   4.4706      9.6345     50.0      1    a(742)       0.0           0.0   
   4.4706      9.6345     50.0      2    a(742)       0.0           1.0   
   4.2134      9.7313     50.0      1    a(742)       0.0           1.0   
   4.2106      9.7998     50.0      1    a(742)       0.0           1.0   
   3.0075      8.4668     50.0      1    a(742)       0.0           1.0   
   2.2209      7.6728     50.0      1    a(742)       0.0           1.0   
   1.0667      6.8953     50.0      1    a(742)       0.0           1.0   
   0.0000      6.3926     50.0      1    a(742)       0.0           1.0

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(298) - the weights assigned in the fit of the model to determine parameter values at 298.15 K only; weight(T) - weights assigned to data at temperatures other than 298.15 K, and used to determine the variation of model parameters and other thermodynamic quantities with temperature.
Solids: 1 = (NH4)2SO4(s), 2 = (NH4)3H(SO4)2(s), 3 = NH4HSO4(s), 4 = NH4H3(SO4)2(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) Osmotic Coefficients from Isopiestic Measurements

  m(NH4)2SO4    mH2SO4        t        osm     ref.   weight(298)  weight(T) 
   0.340124    0.705076     25.0     0.6479    b(1)      1.0         0.0     
   0.283534    0.587766     25.0     0.6426    b(1)      1.0         0.0     
   0.291539    0.604361     25.0     0.6429    b(1)      1.0         0.0     
   0.241165    0.499935     25.0     0.6409    b(1)      1.0         0.0     
   0.231077    0.479023     25.0     0.6410    b(1)      1.0         0.0     
   0.217117    0.450083     25.0     0.6401    b(1)      1.0         0.0     
   0.209860    0.435040     25.0     0.6398    b(1)      1.0         0.0     
   0.198048    0.410552     25.0     0.6403    b(1)      1.0         0.0     
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   0.5000000   0.5000000    50.0     0.6121    b(2)      0.0         1.0     
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   0.6250000   0.6250000    50.0     0.6115    b(2)      0.0         1.0     
   1.0416663   0.2083337    50.0     0.6116    b(2)      0.0         1.0     
   0.2500005   1.2499995    50.0     0.7001    b(2)      0.0         1.0     
   0.7500000   0.7500000    50.0     0.6128    b(2)      0.0         1.0     
   1.2499995   0.2500005    50.0     0.6060    b(2)      0.0         1.0     
   0.2916673   1.4583328    50.0     0.7193    b(2)      0.0         1.0     
   0.8750000   0.8750000    50.0     0.6153    b(2)      0.0         1.0     
   1.4583328   0.2916672    50.0     0.6023    b(2)      0.0         1.0     
   0.3333340   1.6666660    50.0     0.7391    b(2)      0.0         1.0     
   1.0000000   1.0000000    50.0     0.6187    b(2)      0.0         1.0     
   1.6666660   0.3333340    50.0     0.6001    b(2)      0.0         1.0     
   0.3750007   1.8749993    50.0     0.7594    b(2)      0.0         1.0     
   1.1250000   1.1250000    50.0     0.6226    b(2)      0.0         1.0     
   1.8749993   0.3750008    50.0     0.5991    b(2)      0.0         1.0     
   0.4166675   2.0833325    50.0     0.7800    b(2)      0.0         1.0     
   1.2500000   1.2500000    50.0     0.6270    b(2)      0.0         1.0     
   2.0833325   0.4166675    50.0     0.5988    b(2)      0.0         1.0     
   0.4583342   2.2916658    50.0     0.8008    b(2)      0.0         1.0     
   1.3750000   1.3750000    50.0     0.6316    b(2)      0.0         1.0     
   2.2916658   0.4583343    50.0     0.5994    b(2)      0.0         1.0     
   0.5000010   2.4999990    50.0     0.8216    b(2)      0.0         1.0     
   1.5000000   1.5000000    50.0     0.6363    b(2)      0.0         1.0     
   2.4999990   0.5000010    50.0     0.6002    b(2)      0.0         1.0     
   0.5416677   2.7083323    50.0     0.8421    b(2)      0.0         1.0     
   1.6250000   1.6250000    50.0     0.6412    b(2)      0.0         1.0     
   2.7083322   0.5416678    50.0     0.6015    b(2)      0.0         1.0     
   0.5833345   2.9166655    50.0     0.8625    b(2)      0.0         1.0     
   1.7500000   1.7500000    50.0     0.6461    b(2)      0.0         1.0     
   2.9166655   0.5833345    50.0     0.6029    b(2)      0.0         1.0     
   0.6250013   3.1249988    50.0     0.8825    b(2)      0.0         1.0     
   1.8750000   1.8750000    50.0     0.6510    b(2)      0.0         1.0     
   3.1249988   0.6250013    50.0     0.6046    b(2)      0.0         1.0     
   0.6666680   3.3333320    50.0     0.9023    b(2)      0.0         1.0     
   2.0000000   2.0000000    50.0     0.6560    b(2)      0.0         1.0     
   3.3333320   0.6666680    50.0     0.6064    b(2)      0.0         1.0     
   0.7083347   3.5416653    50.0     0.9217    b(2)      0.0         1.0     
   2.1250000   2.1250000    50.0     0.6609    b(2)      0.0         1.0     
   3.5416653   0.7083348    50.0     0.6082    b(2)      0.0         1.0     
   0.7500015   3.7499985    50.0     0.9409    b(2)      0.0         1.0     
   2.2500000   2.2500000    50.0     0.6659    b(2)      0.0         1.0     
   3.7499985   0.7500015    50.0     0.6102    b(2)      0.0         1.0     
   0.7916683   3.9583318    50.0     0.9597    b(2)      0.0         1.0     
   2.3750000   2.3750000    50.0     0.6707    b(2)      0.0         1.0     
   3.9583318   0.7916682    50.0     0.6118    b(2)      0.0         1.0     
   0.8333350   4.1666650    50.0     0.9781    b(2)      0.0         1.0     
   2.5000000   2.5000000    50.0     0.6756    b(2)      0.0         1.0     
   4.1666650   0.8333350    50.0     0.6137    b(2)      0.0         1.0     
   0.8750017   4.3749983    50.0     0.9963    b(2)      0.0         1.0     
   2.6250000   2.6250000    50.0     0.6803    b(2)      0.0         1.0     
   4.3749983   0.8750018    50.0     0.6152    b(2)      0.0         1.0     
   0.9166685   4.5833315    50.0     1.0140    b(2)      0.0         1.0     
   2.7500000   2.7500000    50.0     0.6849    b(2)      0.0         1.0     
   4.5833315   0.9166685    50.0     0.6168    b(2)      0.0         1.0     
   0.9583352   4.7916648    50.0     1.0314    b(2)      0.0         1.0     
   2.8750000   2.8750000    50.0     0.6896    b(2)      0.0         1.0     
   4.7916648   0.9583353    50.0     0.6183    b(2)      0.0         1.0     
   1.0000020   4.9999980    50.0     1.0482    b(2)      0.0         1.0     
   3.0000000   3.0000000    50.0     0.6940    b(2)      0.0         1.0     
   4.9999980   1.0000020    50.0     0.6196    b(2)      0.0         1.0     
   0.050       0.050        25.0     0.7016    b(3)      1.0         0.0     
   0.100       0.100        25.0     0.6712    b(3)      1.0         0.0     
   0.150       0.150        25.0     0.6551    b(3)      1.0         0.0     
   0.200       0.200        25.0     0.6444    b(3)      1.0         0.0     
   0.250       0.250        25.0     0.6368    b(3)      1.0         0.0     
   0.300       0.300        25.0     0.6312    b(3)      1.0         0.0     
   0.350       0.350        25.0     0.6270    b(3)      1.0         0.0     
   0.400       0.400        25.0     0.6240    b(3)      1.0         0.0     
   0.450       0.450        25.0     0.6219    b(3)      1.0         0.0     
   0.500       0.500        25.0     0.6205    b(3)      1.0         0.0     
   0.600       0.600        25.0     0.6195    b(3)      1.0         0.0     
   0.700       0.700        25.0     0.6204    b(3)      1.0         0.0     
   0.800       0.800        25.0     0.6225    b(3)      1.0         0.0     
   0.900       0.900        25.0     0.6255    b(3)      1.0         0.0     
   1.000       1.000        25.0     0.6293    b(3)      1.0         0.0     
   1.100       1.100        25.0     0.6336    b(3)      1.0         0.0     
   1.200       1.200        25.0     0.6383    b(3)      1.0         0.0     
   1.300       1.300        25.0     0.6432    b(3)      1.0         0.0     
   1.400       1.400        25.0     0.6483    b(3)      1.0         0.0     
   1.500       1.500        25.0     0.6534    b(3)      1.0         0.0     
   1.600       1.600        25.0     0.6586    b(3)      1.0         0.0     
   1.700       1.700        25.0     0.6638    b(3)      1.0         0.0     
   1.800       1.800        25.0     0.6690    b(3)      1.0         0.0     
   1.900       1.900        25.0     0.6742    b(3)      1.0         0.0     
   2.000       2.000        25.0     0.6792    b(3)      1.0         0.0     
   2.100       2.100        25.0     0.6842    b(3)      1.0         0.0     
   2.200       2.200        25.0     0.6890    b(3)      1.0         0.0     
   2.300       2.300        25.0     0.6938    b(3)      1.0         0.0     
   2.400       2.400        25.0     0.6984    b(3)      1.0         0.0     
   2.500       2.500        25.0     0.7029    b(3)      1.0         0.0     
   2.600       2.600        25.0     0.7073    b(3)      1.0         0.0     
   2.700       2.700        25.0     0.7116    b(3)      1.0         0.0     
   2.800       2.800        25.0     0.7157    b(3)      1.0         0.0     
   2.900       2.900        25.0     0.7197    b(3)      1.0         0.0     
   3.000       3.000        25.0     0.7235    b(3)      1.0         0.0

Notes and References

Prefix m denotes molality; t - experimental temperature (^oC); osm - stoichiometric osmotic coefficient; ref. - source of data; weight(298) - the weights assigned in the fit of the model to determine parameter values at 298.15 K only; weight(T) - weights assigned to data at temperatures other than 298.15 K, and used to determine the variation of model parameters and other thermodynamic quantities with temperature.
Data b(1) are experimental values, b(2) were calculated by interpolation of the experimental measurements, and b(3) were calculated using the model presented in source b below.
Source: b - S. L. Clegg, S. Milioto and D. A. Palmer (1996) J. Chem. Eng. Data 41, 455-467.

(3) Osmotic Coefficients of Aqueous NH4HSO4 from Vapour Pressure Measurements

   mNH4HSO4     osm         t       ref.    weight(298)  
   27.58087    0.6191     25.0       c         0.0       
   20.78434    0.6397     25.0       c         1.0       
   18.64349    0.6573     25.0       c         1.0       
   13.68152    0.7161     25.0       c         1.0       
   10.11370    0.7542     25.0       c         1.0   
    7.43804    0.7603     25.0       c         1.0   
    6.03329    0.7013     25.0       c         1.0   
    4.85894    0.6745     25.0       c         1.0   
    3.85613    0.6492     25.0       c         1.0   
    2.98307    0.6652     25.0       c         1.0   
    2.26091    0.6434     25.0       c         1.0   
    1.141      0.7016     25.0       c         0.0

Notes and References

Prefix m denotes molality; osm - stoichiometric osmotic coefficient; t - experimental temperature (^oC); ref. - source of data; weight(298) - the weights assigned in the fit of the model to determine parameter values at 298.15 K (normalised).
Sources: c - I. N. Tang and H. R. Munkelwitz (1977) J. Aerosol Sci. 8, 321-330;

(4) Osmotic Coefficients of Aqueous (NH4)3H(SO4)2 from Vapour pressure Measurements

  m(NH4)3H(SO4)2    osm         t     ref.   weight(298)   weight(T)   
     0.78479       0.591      25.0     d        1.0          0.0      
     1.08816       0.617      25.0     d        1.0          0.0      
     1.39355       0.604      25.0     d        1.0          0.0      
     1.83012       0.610      25.0     d        1.0          0.0      
     2.35716       0.624      25.0     d        1.0          0.0      
     2.93493       0.627      25.0     d        1.0          0.0      
     3.60310       0.639      25.0     d        1.0          0.0      
     4.11124       0.638      25.0     d        1.0          0.0      
     4.37473       0.656      25.0     d        1.0          0.0      
     0.7704        0.610      20.0     e        0.0          1.0      
     1.0914        0.610      20.0     e        0.0          1.0      
     1.4064        0.616      20.0     e        0.0          1.0      
     1.8172        0.605      20.0     e        0.0          1.0      
     2.3755        0.616      20.0     e        0.0          1.0      
     2.9289        0.650      20.0     e        0.0          1.0      
     3.5868        0.651      20.0     e        0.0          1.0      
     4.0935        0.638      20.0     e        0.0          1.0      
     4.3468        0.649      20.0     e        0.0          1.0      
     0.7992        0.605      30.0     e        0.0          1.0      
     1.0849        0.608      30.0     e        0.0          1.0      
     1.3917        0.617      30.0     e        0.0          1.0      
     1.8172        0.651      30.0     e        0.0          0.0      
     2.3755        0.625      30.0     e        0.0          1.0      
     2.9289        0.638      30.0     e        0.0          1.0      
     3.5868        0.638      30.0     e        0.0          1.0      
     4.0935        0.647      30.0     e        0.0          1.0      
     4.3817        0.663      30.0     e        0.0          1.0

Notes and References

Prefix m denotes molality; t - experimental temperature (^oC); osm - stoichiometric osmotic coefficient; ref. - source of data; weight(298) - the weights assigned in the fit of the model to determine parameter values at 298.15 K only; weight(T) - weights assigned to data at temperatures other than 298.15 K, and used to determine the variation of model parameters and other thermodynamic quantities with temperature.
Sources: d - I. N. Tang and H. R. Munkelwitz (1994) J. Geophys. Res. 99, 18801-18808; e - I. N. Tang, H. R. Munkelwitz and J. G. Davis (1978) J. Aerosol Sci. 9, 505-511.

(5) Osmotic Coefficients of Aqueous NH4HSO4 from Electrodynamic Balance Measurements

   mNH4HSO4       osm       t    ref.  weight(298)   
   90.780344    0.33362    25     f        -         
   83.797240    0.34948    25     f        -    
   79.226482    0.36159    25     f        -    
   75.128560    0.36910    25     f        -    
   72.624275    0.37374    25     f        -    
   66.022068    0.39828    25     f        -    
   64.080243    0.39770    25     f       1.0   
   57.334954    0.43094    25     f       1.0   
   54.468206    0.44444    25     f       1.0   
   51.874482    0.45267    25     f       1.0   
   47.363658    0.47625    25     f       1.0   
   44.463842    0.48749    25     f       1.0   
   41.108080    0.50682    25     f       1.0   
   38.223303    0.52402    25     f       1.0   
   36.312138    0.54087    25     f       1.0   
   34.582988    0.55145    25     f       1.0   
   33.011034    0.56098    25     f       1.0   
   30.686313    0.59177    25     f       1.0   
   30.686313    0.58029    25     f       1.0   
   29.442274    0.58727    25     f       1.0   
   27.932413    0.61296    25     f       1.0   
   26.897880    0.61197    25     f       1.0   
   25.937241    0.61610    25     f       1.0   
   25.334049    0.61839    25     f       1.0   
   23.942069    0.63510    25     f       1.0   
   23.177960    0.64952    25     f       1.0   
   22.007356    0.65712    25     f       1.0   
   21.360081    0.65686    25     f       1.0   
   20.554040    0.66887    25     f       1.0   
   18.782140    0.68818    25     f       1.0   
   18.006019    0.69574    25     f       1.0   
   17.429826    0.70379    25     f       1.0   
   16.759448    0.70902    25     f       1.0   
   16.381415    0.71002    25     f       1.0   
   15.562345    0.73143    25     f       1.0   
   15.130057    0.73613    25     f       1.0   
   14.821281    0.72706    25     f       1.0   
   14.524855    0.72557    25     f       1.0   
   14.333738    0.72705    25     f       1.0   
   14.056311    0.72896    25     f       1.0

Notes and References

Prefix m denotes molality; osm - stoichiometric osmotic coefficient; t - experimental temperature (^oC); ref. - source of data; weight(298) - the weights assigned in the fit of the model to determine parameter values at 298.15 K (normalised).
Sources: f - J. F. Spann (1984) Ph.D Thesis, University of Arkansas, Fayetteville.
The experiments of Spann were conducted at room temperature, and are assumed to yield results equivalent to what would be obtained at 298.15 K.

(6) Osmotic Coefficients of Aqueous H2SO4 - (NH4)2SO4 Mixtures from Electrodynamic Balance Measurements

      mH           mNH4        mSO4       t       osm        ref.  weight(298)   
    3.526143     8.632971    6.0795571   25      0.6539       f       1.0        
    3.612147     8.843531    6.2278390   25      0.6383       f       1.0        
    3.778011     9.249612    6.5138112   25      0.6339       f       1.0        
    3.959840     9.694780    6.8273102   25      0.6503       f       1.0        
    4.160057    10.184966    7.1725112   25      0.6631       f       1.0        
    4.292696    10.509704    7.4012000   25      0.6861       f       1.0        
    4.515183    11.054414    7.7847988   25      0.6627       f       1.0        
    4.716497    11.547286    8.1318917   25      0.6749       f       1.0        
    4.969732    12.167275    8.5685034   25      0.6600       f       1.0        
    5.178252    12.677790    8.9280210   25      0.6808       f       1.0        
    5.365870    13.137130    9.2515000   25      0.6756       f       1.0        
    5.652596    13.839114    9.7458550   25      0.6681       f       1.0        
    5.876905    14.388285   10.1325952   25      0.6688       f       1.0        
    6.328975    15.495076   10.9120256   25      0.6539       f       1.0        
    7.794632    19.083410   13.4390211   25      0.6434       f       1.0        
    8.610350    21.080511   14.8454302   25      0.6229       f       1.0        
    9.373292    22.948404   16.1608481   25      0.6106       f       1.0        
    9.616754    23.544467   16.5806104   25      0.6015       f       1.0        
   10.578429    25.898913   18.2386714   25      0.5882       f       1.0        
   12.341501    30.215399   21.2784500   25      0.5576       f       1.0        
   14.240193    34.863922   24.5520577   25      0.5224       f       1.0        
   17.630716    43.164856   30.3977857   25      0.4906       f       1.0        
   20.569168    50.358998   35.4640833   25      0.4652       f        -         
   25.534140    62.514619   44.0243793   25      0.4255       f        -         
   28.745566    70.377077   49.5613220   25      0.4101       f        -         
   35.261431    86.329711   60.7955714   25      0.3664       f        -         
   41.138337   100.71799    70.9281667   25      0.3448       f        -

Notes and References

Prefix m denotes molality; osm - stoichiometric osmotic coefficient; t - experimental temperature (^oC); ref. - source of data; weight(298) - the weight assigned in the fit of the model to determine parameter values at 298.15 K (normalised).
Sources: f - J. F. Spann (1984) Ph.D Thesis, University of Arkansas, Fayetteville.
The experiments of Spann were conducted at room temperature, and are assumed to yield results equivalent to what would be obtained at 298.15 K.

(7) Water Activities of Aqueous (NH4)2SO4 - NH4HSO4 Mixtures from Electrodynamic Balance Measurements

    mNH42SO4     mNH4HSO4       t        aW      ref.    weight(298)
    3.036297     0.000000      25       0.90      f          0.0   
    0.000000     2.738443      25       0.90      f          0.0   
    5.848047     0.000000      25       0.80      f          0.0   
    5.107281     0.692866      25       0.80      f          0.0   
    4.947123     1.085458      25       0.80      f          0.0   
    4.701901     1.131820      25       0.80      f          0.0   
    4.595048     1.466350      25       0.80      f          0.0   
    3.924422     1.866849      25       0.80      f          0.0   
    2.639006     3.693344      25       0.80      f          0.0   
    0.000000     5.517738      25       0.80      f          0.0   
    8.982667     0.000000      25       0.70      f          0.0   
    7.814868     1.084280      25       0.70      f          0.0   
    7.449002     1.638029      25       0.70      f          0.0   
    7.303970     1.792930      25       0.70      f          0.0   
    5.850043     2.869160      25       0.70      f          0.0   
    5.263720     5.184238      25       0.70      f          0.0   
    3.945619     5.709001      25       0.70      f          0.0   
    3.404222     6.455064      25       0.70      f          0.0   
    2.733552     7.001871      25       0.70      f          0.0   
    2.394376     8.053537      25       0.70      f          0.0   
    1.603617     7.801556      25       0.70      f          0.0   
    0.812544     8.567999      25       0.70      f          0.0   
    0.000000     8.267121      25       0.70      f          0.0   
   13.024149     0.000000      25       0.60      f          0.0   
   12.136188     1.708974      25       0.60      f          0.0   
   11.375647     2.505276      25       0.60      f          0.0   
   10.810398     2.704720      25       0.60      f          0.0   
   10.465574     3.326077      25       0.60      f          0.0   
    8.676318     4.201502      25       0.60      f          0.0   
    7.811538     7.625895      25       0.60      f          0.0   
    6.248558     8.822608      25       0.60      f          0.0   
    5.184450     9.792829      25       0.60      f          0.0   
    4.257991    10.759691      25       0.60      f          0.0   
    3.605274    12.005165      25       0.60      f          0.0   
    2.669002    12.146255      25       0.60      f          0.0   
    1.171662    12.447682      25       0.60      f          0.0   
    0.000000    12.336248      25       0.60      f          0.0   
   19.676973     0.000000      25       0.50      f          0.0   
   16.924427     2.395471      25       0.50      f          0.0   
   16.552279     3.622722      25       0.50      f          0.0   
   15.818239     3.944113      25       0.50      f          0.0   
   15.308721     4.891684      25       0.50      f          0.0   
   13.081967     6.329470      25       0.50      f          0.0   
   11.717815    11.345997      25       0.50      f          0.0   
    9.793960    13.797774      25       0.50      f          0.0   
    8.103884    15.499124      25       0.50      f          0.0   
    6.412646    16.451527      25       0.50      f          0.0   
    5.684295    18.717781      25       0.50      f          0.0   
    3.688305    18.038740      25       0.50      f          0.0   
    1.752610    18.723870      25       0.50      f          0.0   
    0.000000    18.266016      25       0.50      f          0.0   
   30.848549     0.000000      25       0.40      f          0.0   
   18.682611     9.072457      25       0.40      f          0.0   
   18.736237    18.197023      25       0.40      f          0.0   
   16.003512    22.927153      25       0.40      f          0.0   
   13.442396    25.344578      25       0.40      f          0.0   
   10.381157    26.658510      25       0.40      f          0.0   
    9.253574    30.402623      25       0.40      f          0.0   
    5.960835    28.946422      25       0.40      f          0.0   
    2.741731    29.079732      25       0.40      f          0.0   
    0.000000    26.945904      25       0.40      f          0.0   
   25.256106    35.267826      25       0.30      f          0.0   
   21.173091    39.922323      25       0.30      f          0.0   
   17.032508    43.696653      25       0.30      f          0.0   
   14.716289    49.003687      25       0.30      f          0.0   
    9.663159    47.639162      25       0.30      f          0.0   
    4.381506    46.638007      25       0.30      f          0.0   
    0.000000    45.219526      25       0.30      f          0.0   
   25.653481    84.915108      25       0.20      f           -    
   18.234773    89.845551      25       0.20      f           -    
    7.714211    83.536686      25       0.20      f           -    
    0.000000    86.875030      25       0.20      f           -    
    7.077866     2.199726      25       0.70      f          0.0

Notes and References

Prefix m denotes molality; aW - water activity; t - experimental temperature (^oC); ref. - source of data; weight(298) - the weight assigned in the fit of the model to determine parameter values at 298.15 K (normalised).
Sources: f - J. F. Spann (1984) Ph.D Thesis, University of Arkansas, Fayetteville.
The experiments of Spann were conducted at room temperature, and are assumed to yield results equivalent to what would be obtained at 298.15 K.
These data were used for comparison only, and were not fitted.

(8) Water Activities of Aqueous H2SO4 - (NH4)2SO4 Mixtures from Electrodynamic Balance Measurements

  mH2SO4   m(NH4)2SO4    t        aW       ref.   weight(298)
   2.484     2.484      25       0.8190      g        0.0  
   2.832     2.832      25       0.7800      g        0.0  
   3.450     3.450      25       0.7330      g        0.0  
   3.060     3.060      25       0.7800      g        0.0  
   4.054     4.054      25       0.7060      g        0.0  
   4.718     4.718      25       0.6640      g        0.0  
   5.409     5.409      25       0.6310      g        0.0  
   6.153     6.153      25       0.5990      g        0.0  
   6.757     6.757      25       0.5770      g        0.0  
   7.482     7.482      25       0.5480      g        0.0  
   8.512     8.512      25       0.5200      g        0.0  
   9.209     9.209      25       0.4970      g        0.0  
  10.471    10.471      25       0.4660      g        0.0  
  11.769    11.769      25       0.4350      g        0.0  
  12.930    12.930      25       0.4140      g        0.0  
  14.088    14.088      25       0.3950      g        0.0  
  15.175    15.175      25       0.3740      g        0.0  
  16.014    16.014      25       0.3640      g        0.0  
  17.056    17.056      25       0.3550      g        0.0  
  19.264    19.264      25       0.3250      g        0.0  
  21.866    21.866      25       0.2890      g        0.0  
  29.476    29.476      25       0.2640      g        0.0  
  75.665    75.665      25       0.2510      g         -   
   3.738     1.869      25       0.7470      g        0.0  
   3.229     1.615      25       0.7990      g        0.0  
   4.419     2.210      25       0.7060      g        0.0  
   5.078     2.539      25       0.6670      g        0.0  
   5.789     2.895      25       0.6230      g        0.0  
   6.571     3.285      25       0.5810      g        0.0  
   7.260     3.630      25       0.5520      g        0.0  
   8.233     4.117      25       0.5100      g        0.0  
   8.927     4.463      25       0.4840      g        0.0  
   9.633     4.817      25       0.4570      g        0.0  
  10.362     5.181      25       0.4330      g        0.0  
  11.465     5.732      25       0.4020      g        0.0  
  12.188     6.094      25       0.3820      g        0.0  
  13.516     6.758      25       0.3470      g        0.0  
  14.249     7.124      25       0.3290      g        0.0  
  15.311     7.656      25       0.3070      g        0.0  
  15.865     7.933      25       0.2900      g        0.0  
  17.105     8.552      25       0.2710      g        0.0  
  17.799     8.900      25       0.2600      g        0.0  
  18.711     9.356      25       0.2270      g        0.0  
   4.372     2.186      25       0.7460      g        0.0  
   5.174     2.587      25       0.6800      g        0.0  
   6.052     3.026      25       0.6220      g        0.0  
   6.939     3.469      25       0.5730      g        0.0  
   8.511     4.256      25       0.5030      g        0.0  
   9.778     4.889      25       0.4500      g        0.0  
  11.118     5.559      25       0.4030      g        0.0  
  12.653     6.326      25       0.3630      g        0.0  
  14.117     7.059      25       0.3260      g        0.0  
  15.573     7.786      25       0.2960      g        0.0  
  17.118     8.559      25       0.2660      g        0.0  
  18.548     9.274      25       0.2430      g        0.0  
  23.147    11.573      25       0.2170      g        0.0

Notes and References

Prefix m denotes molality; aW - water activity; t - experimental temperature (^oC); ref. - source of data; weight(298) - the weight assigned in the fit of the model to determine parameter values at 298.15 K (normalised).
Source: g - Y. P. Kim, B. K.-L. Pun, C. K. Chan, R. C. Flagan, and J. H. Seinfeld (1994) Aerosol Science and Technol. 20, 275-284.
The experiments were conducted at temperatures between 23.6 ^oC and 25.5 ^oC, and are assumed to yield results equivalent to what would be obtained at 298.15 K.
These data were used for comparison only, and were found to agree well with other measurements (see section 3.7 of Clegg et al. (1998a)).

(9) Water Activities of Aqueous H2SO4 - (NH4)2SO4 Mixtures from Isopiestic Measurements

    mH2SO4   m(NH4)2SO4     t            aW       ref.   weight(298)  
    0.050      0.191      25.0          0.992      h         0.0   
    0.075      0.168      25.0          0.992      h         0.0   
    0.102      0.146      25.0          0.992      h         0.0   
    0.128      0.123      25.0          0.992      h         0.0   
    0.154      0.098      25.0          0.992      h         0.0   
    0.180      0.074      25.0          0.992      h         0.0   
    0.204      0.049      25.0          0.992      h         0.0   
    0.226      0.024      25.0          0.992      h         0.0   
    0.101      0.403      25.0          0.983      h         0.0   
    0.154      0.359      25.0          0.983      h         0.0   
    0.206      0.309      25.0          0.983      h         0.0   
    0.259      0.259      25.0          0.983      h         0.0   
    0.310      0.207      25.0          0.983      h         0.0   
    0.359      0.154      25.0          0.983      h         0.0   
    0.406      0.102      25.0          0.983      h         0.0   
    0.447      0.050      25.0          0.983      h         0.0   
    0.194      0.875      25.0          0.965      h         0.0   
    0.296      0.782      25.0          0.965      h         0.0   
    0.401      0.679      25.0          0.965      h         0.0   
    0.502      0.567      25.0          0.965      h         0.0   
    0.598      0.451      25.0          0.965      h         0.0   
    0.687      0.333      25.0          0.965      h         0.0   
    0.769      0.217      25.0          0.965      h         0.0   
    0.847      0.106      25.0          0.965      h         0.0   
    0.304      1.502      25.0          0.943      h         0.0   
    0.470      1.354      25.0          0.943      h         0.0   
    0.637      1.179      25.0          0.943      h         0.0   
    0.798      0.984      25.0          0.943      h         0.0   
    0.946      0.778      25.0          0.943      h         0.0   
    1.083      0.572      25.0          0.943      h         0.0   
    1.205      0.371      25.0          0.943      h         0.0   
    1.315      0.180      25.0          0.943      h         0.0   
    0.408      2.179      25.0          0.919      h         0.0   
    0.633      1.971      25.0          0.919      h         0.0   
    0.859      1.720      25.0          0.919      h         0.0   
    1.079      1.440      25.0          0.919      h         0.0   
    1.280      1.139      25.0          0.919      h         0.0   
    1.453      0.832      25.0          0.919      h         0.0   
    1.610      0.537      25.0          0.919      h         0.0   
    1.746      0.259      25.0          0.919      h         0.0   
    0.505      2.827      25.0          0.894      h         0.0   
    0.789      2.576      25.0          0.894      h         0.0   
    1.081      2.270      25.0          0.894      h         0.0   
    1.358      1.901      25.0          0.894      h         0.0   
    1.603      1.496      25.0          0.894      h         0.0   
    1.818      1.091      25.0          0.894      h         0.0   
    2.000      0.700      25.0          0.894      h         0.0   
    2.159      0.336      25.0          0.894      h         0.0   
    0.603      3.551      25.0          0.868      h         0.0   
    0.947      3.255      25.0          0.868      h         0.0   
    1.306      2.886      25.0          0.868      h         0.0   
    1.650      2.431      25.0          0.868      h         0.0   
    1.946      1.911      25.0          0.868      h         0.0   
    2.197      1.387      25.0          0.868      h         0.0   
    2.408      0.887      25.0          0.868      h         0.0   
    2.582      0.423      25.0          0.868      h         0.0   
    0.695      4.267      25.0          0.841      h         0.0   
    1.100      3.937      25.0          0.841      h         0.0   
    1.529      3.518      25.0          0.841      h         0.0   
    1.938      2.973      25.0          0.841      h         0.0   
    2.292      2.344      25.0          0.841      h         0.0   
    2.573      1.692      25.0          0.841      h         0.0   
    2.795      1.072      25.0          0.841      h         0.0   
    2.987      0.509      25.0          0.841      h         0.0   
    1.252      4.637      25.0          0.812      h         0.0   
    1.746      4.158      25.0          0.812      h         0.0   
    2.233      3.544      25.0          0.812      h         0.0   
    2.635      2.789      25.0          0.812      h         0.0   
    2.938      1.999      25.0          0.812      h         0.0   
    3.170      1.258      25.0          0.812      h         0.0   
    3.389      0.598      25.0          0.812      h         0.0   
    1.990      4.855      25.0          0.785      h         0.0   
    2.560      4.165      25.0          0.785      h         0.0   
    3.011      3.265      25.0          0.785      h         0.0   
    3.337      2.326      25.0          0.785      h         0.0   
    3.585      1.458      25.0          0.785      h         0.0   
    3.772      0.682      25.0          0.785      h         0.0   
    0.251      0.000      25.0          0.992      h         0.0   
    0.253      0.000      25.0          0.992      h         0.0   
    0.000      0.234      25.0          0.992      h         0.0   
    0.493      0.000      25.0          0.983      h         0.0   
    0.493      0.000      25.0          0.983      h         0.0   
    0.000      0.482      25.0          0.983      h         0.0   
    0.925      0.000      25.0          0.965      h         0.0   
    0.926      0.000      25.0          0.965      h         0.0   
    0.000      1.030      25.0          0.965      h         0.0   
    1.418      0.000      25.0          0.943      h         0.0   
    1.420      0.000      25.0          0.943      h         0.0   
    0.000      1.752      25.0          0.943      h         0.0   
    1.869      0.000      25.0          0.919      h         0.0   
    1.870      0.000      25.0          0.919      h         0.0   
    0.000      2.481      25.0          0.919      h         0.0   
    2.310      0.000      25.0          0.894      h         0.0   
    2.312      0.000      25.0          0.894      h         0.0   
    0.000      3.211      25.0          0.894      h         0.0   
    2.745      0.000      25.0          0.868      h         0.0   
    2.744      0.000      25.0          0.868      h         0.0   
    0.000      3.977      25.0          0.868      h         0.0   
    3.156      0.000      25.0          0.841      h         0.0   
    3.155      0.000      25.0          0.841      h         0.0   
    0.000      4.767      25.0          0.841      h         0.0   
    3.560      0.000      25.0          0.812      h         0.0   
    3.562      0.000      25.0          0.812      h         0.0   
    3.932      0.000      25.0          0.785      h         0.0   
    3.932      0.000      25.0          0.785      h         0.0

Notes and References

Prefix m denotes molality; aW - water activity; t - experimental temperature (^oC); ref. - source of data; weight(298) - the weight assigned in the fit of the model to determine parameter values at 298.15 K (normalised).
Source: h - S. K. Park, Y. Awakura and H. Majima (1989) Metal. Trans. 20B, 13-20.
The measurements were incorrectly listed by Clegg et al. (1998a) as being at 15 ^oC.
These data were used for comparison only, and were found to agree well with other measurements (see section 3.7 of Clegg et al. (1998a)).

(10) Osmotic Coefficients of Aqueous NH4HSO4 from Electrodynamic Balance Measurements

  mNH4HSO4     osm          t      ref.   weight(298)
   27.998      0.5856     25.0      d        0.0    
   27.998      0.5913     25.0      d        0.0    
   28.482      0.5932     25.0      d        0.0    
   30.246      0.5629     25.0      d        0.0    
   30.597      0.5838     25.0      d        0.0    
   31.399      0.5762     25.0      d        0.0    
   31.625      0.5753     25.0      d        0.0    
   32.401      0.5715     25.0      d        0.0    
   33.217      0.5610     25.0      d        0.0    
   33.727      0.5648     25.0      d        0.0    
   38.225      0.5106     25.0      d        0.0    
   40.327      0.5095     25.0      d        0.0    
   42.539      0.5177     25.0      d        0.0    
   48.306      0.4701     25.0      d        0.0    
   48.306      0.4981     25.0      d        0.0    
   48.841      0.4952     25.0      d        0.0    
   49.391      0.4895     25.0      d        0.0    
   49.577      0.4886     25.0      d        0.0    
   51.917      0.4816     25.0      d        0.0    
   53.606      0.4729     25.0      d        0.0    
   53.606      0.4739     25.0      d        0.0    
   54.269      0.4756     25.0      d        0.0    
   57.585      0.4565     25.0      d        0.0    
   57.585      0.4620     25.0      d        0.0    
   60.772      0.4383     25.0      d        0.0    
   61.054      0.4456     25.0      d        0.0    
   61.911      0.4464     25.0      d        0.0    
   64.019      0.4386     25.0      d        0.0    
   65.284      0.4374     25.0      d        0.0    
   66.939      0.4306     25.0      d        0.0    
   68.685      0.4230     25.0      d        0.0    
   70.900      0.4180     25.0      d        0.0    
   68.685      0.4339     25.0      d        0.0    
   29.502      0.5790     25.0      d        0.0    
   28.668      0.5960     25.0      d        0.0    
   29.047      0.5880     25.0      d        0.0    
   29.111      0.5860     25.0      d        0.0    
   29.111      0.5860     25.0      d        0.0    
   29.240      0.5830     25.0      d        0.0    
   28.919      0.5830     25.0      d        0.0    
   28.668      0.5870     25.0      d        0.0    
   28.919      0.5750     25.0      d        0.0    
   28.421      0.5820     25.0      d        0.0    
   27.881      0.5920     25.0      d        0.0    
   27.417      0.5870     25.0      d        0.0    
   27.079      0.5930     25.0      d        0.0    
   26.114      0.5980     25.0      d        0.0    
   25.557      0.6040     25.0      d        0.0    
   24.109      0.6120     25.0      d        0.0    
   22.620      0.6290     25.0      d        0.0    
   21.033      0.6450     25.0      d        0.0    
   19.801      0.6610     25.0      d        0.0    
   19.140      0.6600     25.0      d        0.0    
   17.845      0.6790     25.0      d        0.0    
   16.526      0.6990     25.0      d        0.0    
   14.867      0.7250     25.0      d        0.0    
   14.397      0.7080     25.0      d        0.0    
   13.388      0.7200     25.0      d        0.0    
   13.321      0.6970     25.0      d        0.0    
   13.201      0.6890     25.0      d        0.0    
   11.891      0.7220     25.0      d        0.0    
   11.457      0.7210     25.0      d        0.0    
   10.669      0.7360     25.0      d        0.0    
   10.400      0.7300     25.0      d        0.0    
   10.021      0.7240     25.0      d        0.0    
    9.467      0.7300     25.0      d        0.0    
    9.267      0.7260     25.0      d        0.0    
    8.757      0.7330     25.0      d        0.0    
    8.284      0.7330     25.0      d        0.0    
    8.051      0.7220     25.0      d        0.0    
    7.645      0.7150     25.0      d        0.0    
    7.359      0.7230     25.0      d        0.0    
    7.159      0.7160     25.0      d        0.0    
    6.798      0.7100     25.0      d        0.0    
    6.545      0.7040     25.0      d        0.0    
    6.313      0.6970     25.0      d        0.0    
    6.108      0.6970     25.0      d        0.0    
    5.992      0.6910     25.0      d        0.0    
    5.906      0.6840     25.0      d        0.0    
    5.704      0.6860     25.0      d        0.0    
    5.578      0.6720     25.0      d        0.0    
    5.643      0.6750     25.0      d        0.0    
    5.670      0.6750     25.0      d        0.0    
    5.697      0.6760     25.0      d        0.0    
    5.794      0.6750     25.0      d        0.0    
    5.858      0.6790     25.0      d        0.0    
    5.951      0.6800     25.0      d        0.0    
    6.022      0.6830     25.0      d        0.0    
    6.119      0.6780     25.0      d        0.0    
    6.157      0.6840     25.0      d        0.0    
    6.307      0.6780     25.0      d        0.0    
    6.405      0.6830     25.0      d        0.0    
    6.516      0.6870     25.0      d        0.0    
    6.674      0.6840     25.0      d        0.0    
    6.894      0.6890     25.0      d        0.0    
    7.098      0.6970     25.0      d        0.0    
    7.254      0.6980     25.0      d        0.0    
    7.484      0.7020     25.0      d        0.0    
    7.840      0.6960     25.0      d        0.0    
    8.181      0.6970     25.0      d        0.0    
    8.608      0.6950     25.0      d        0.0    
    9.556      0.6840     25.0      d        0.0    
    9.783      0.7080     25.0      d        0.0    
   10.067      0.7010     25.0      d        0.0    
   10.408      0.7000     25.0      d        0.0    
   10.962      0.6890     25.0      d        0.0    
   11.629      0.7020     25.0      d        0.0    
   11.660      0.7030     25.0      d        0.0    
   12.244      0.6890     25.0      d        0.0    
   12.680      0.6970     25.0      d        0.0    
   13.135      0.6930     25.0      d        0.0    
   13.623      0.6830     25.0      d        0.0    
   14.350      0.6660     25.0      d        0.0    
   14.935      0.6790     25.0      d        0.0    
   16.651      0.6530     25.0      d        0.0    
   17.467      0.6600     25.0      d        0.0    
   18.016      0.6540     25.0      d        0.0    
   20.072      0.6420     25.0      d        0.0    
   21.408      0.6320     25.0      d        0.0    
   23.847      0.6180     25.0      d        0.0    
   24.742      0.6140     25.0      d        0.0    
   25.857      0.6070     25.0      d        0.0    
   25.807      0.6090     25.0      d        0.0    
   26.375      0.6050     25.0      d        0.0    
   27.763      0.5920     25.0      d        0.0    
   28.731      0.5930     25.0      d        0.0    
   31.399      0.5640     25.0      d        0.0    
   32.969      0.5506     25.0      d        0.0    
   35.932      0.5438     25.0      d        0.0    
   38.901      0.5360     25.0      d        0.0    
   45.007      0.4827     25.0      d        0.0    
   47.780      0.4870     25.0      d        0.0    
   50.143      0.4829     25.0      d        0.0    
   47.436      0.5620     25.0      d        0.0   
   52.962      0.4869     25.0      d        0.0    
   65.284      0.3952     25.0      d        0.0    
   71.284      0.4269     25.0      d        0.0    
   74.930      0.4080     25.0      d        0.0    
   76.669      0.4013     25.0      d        0.0    
   76.669      0.4040     25.0      d        0.0    
   78.032      0.4055     25.0      d        0.0    
   80.903      0.3976     25.0      d        0.0    
   86.761      0.3793     25.0      d        0.0    
   87.920      0.3861     25.0      d        0.0    
   92.873      0.3726     25.0      d        0.0    
   97.687      0.3618     25.0      d        0.0    
   97.687      0.3687     25.0      d        0.0    
  103.028      0.3518     25.0      d        0.0    
  108.987      0.3400     25.0      d        0.0    
  110.822      0.3404     25.0      d        0.0    
  117.747      0.3226     25.0      d        0.0    
  122.099      0.3123     25.0      d        0.0    
  125.594      0.3199     25.0      d        0.0    
  130.578      0.3120     25.0      d        0.0    
  134.562      0.3078     25.0      d         -     
  140.299      0.3031     25.0      d         -     
  156.981      0.2775     25.0      d         -     
  171.280      0.2679     25.0      d         -     
  171.280      0.2748     25.0      d         -     
  185.746      0.2658     25.0      d         -     
  206.057      0.2428     25.0      d         -     
  216.211      0.2369     25.0      d         -     
  231.354      0.2238     25.0      d         -     
  263.732      0.1978     25.0      d         -

Notes and References

Prefix m denotes molality; osm - osmotic coefficient; t - experimental temperature (^oC); ref. - source of data; weight(298) - the weight assigned in the fit of the model to determine parameter values at 298.15 K (normalised).
Source: d - I. N. Tang and H. R. Munkelwitz (1994) J. Geophys. Res. 99, 18801-18808.
These data were standardised to agree with existing (bulk) measurements at low, subsaturated, molalities and are plotted in Figure 14 of Clegg et al. (1998a). They do not agree with other available data at very high concentration, but are included here for reference.

(11) Degrees of Dissociation of HSO4⁻ Ion in Aqueous NH4HSO4

  mNH4HSO4       alpha          t      ref.   weight(T)  weight(298)  
 10.441105       0.210        25.0      i       0.0         0.0        
  8.289717       0.243        25.0      i       0.0         0.0        
  6.441703       0.280        25.0      i       0.0         0.0        
  4.655643       0.324        25.0      i       0.0         0.0        
  3.370414       0.345        25.0      i       0.0         0.0        
  2.206058       0.351        25.0      i       0.0         0.0        
  1.102787       0.349        25.0      i       0.0         0.0        
  1.010489       0.350        25.0      i       0.0         0.0        
  0.954121       0.350        25.0      i       0.0         0.0        
  0.863932       0.350        25.0      i       0.0         0.0        
  0.706286       0.352        25.0      i       0.0         0.0        
  0.662590       0.352        25.0      i       0.0         0.0        
  0.481348       0.357        25.0      i       0.0         0.0        
  0.437310       0.358        25.0      i       0.0         0.0        
  0.228326       0.365        25.0      i       0.0         0.0        
  9.94204        0.36508      25.0      j       0.0         1.0        
  7.44136        0.38462      25.0      j       0.0         1.0        
  5.30243        0.42105      25.0      j       0.0         1.0        
  3.64615        0.43333      25.0      j       0.0         1.0        
  2.20996        0.42574      25.0      j       0.0         1.0        
  1.06603        0.44792      25.0      j       0.0         1.0        
  0.63069        0.43860      25.0      j       0.0         1.0        
  0.40480        0.48718      25.0      j       0.0         1.0        
  0.20858        0.55556      25.0      j       0.0         1.0        
  0.655          0.456        25.0      k       0.0         1.0        
  1.32           0.445        25.0      k       0.0         1.0        
  3.09           0.400        25.0      k       0.0         1.0        
  4.10           0.377        25.0      k       0.0         1.0        
  5.23           0.400        25.0      k       0.0         1.0        
  7.23           0.360        25.0      k       0.0         1.0        
  8.61           0.351        25.0      k       0.0         1.0        
 10.12525        0.45161       0.0      j       0.0         0.0        
  5.34543        0.56757       0.0      j       0.0         0.0        
  2.21938        0.65823       0.0      j       0.0         0.0        
  0.63202        0.68750       0.0      j       0.0         0.0        
  0.40524        0.74074       0.0      j       0.0         0.0        
  9.87451        0.28000      50.0      j       1.0         0.0        
  7.37962        0.30189      50.0      j       1.0         0.0        
  5.27791        0.30380      50.0      j       1.0         0.0        
  3.61375        0.33333      50.0      j       1.0         0.0        
  2.20239        0.31429      50.0      j       1.0         0.0        
  1.06342        0.32979      50.0      j       1.0         0.0        
  0.40449        0.36508      50.0      j       1.0         0.0        
  0.655          0.339        50.0      k       1.0         0.0        
  1.32           0.299        50.0      k       1.0         0.0        
  3.09           0.285        50.0      k       1.0         0.0        
  4.10           0.284        50.0      k       1.0         0.0        
  5.23           0.280        50.0      k       1.0         0.0        
  7.23           0.292        50.0      k       1.0         0.0        
  8.61           0.275        50.0      k       1.0         0.0

Notes and References

Prefix m denotes molality; alpha - the degree of dissociation of the bisulphate ion (mSO4/(mSO4 + mHSO4)); t - experimental temperature (^oC); ref. - source of data; weight(298) - the weights assigned in the fit of the model to determine parameter values at 298.15 K only; weight(T) - weights assigned to data at temperatures other than 298.15 K, and used to determine the variation of model parameters and other thermodynamic quantities with temperature.
Sources: i - D. E. Irish and H. Chen (1970) J. Phys. Chem. 74, 3796-3801; j - T. F. Young, L. F. Maranville and H. M. Smith (1959) In: Structure of Electrolytic Solutions, Ed. W. J. Hamer, Wiley, New York, pp35-63; k - B. S. W. Dawson, D. E. Irish and G. E. Toogood (1986) J. Phys. Chem. 90, 334-341.

Model II: Data for Aqueous H+ - NH4+ - SO42−

The System

Weights

The Data

(1) Solubilities of Solid Phases

(2) Osmotic Coefficients from Isopiestic Measurements

(3) Osmotic Coefficients of Aqueous NH4HSO4 from Vapour Pressure Measurements

(4) Osmotic Coefficients of Aqueous (NH4)3H(SO4)2 from Vapour pressure Measurements

(5) Osmotic Coefficients of Aqueous NH4HSO4 from Electrodynamic Balance Measurements

(6) Osmotic Coefficients of Aqueous H2SO4 - (NH4)2SO4 Mixtures from Electrodynamic Balance Measurements

(7) Water Activities of Aqueous (NH4)2SO4 - NH4HSO4 Mixtures from Electrodynamic Balance Measurements

(8) Water Activities of Aqueous H2SO4 - (NH4)2SO4 Mixtures from Electrodynamic Balance Measurements

(9) Water Activities of Aqueous H2SO4 - (NH4)2SO4 Mixtures from Isopiestic Measurements

(10) Osmotic Coefficients of Aqueous NH4HSO4 from Electrodynamic Balance Measurements

(11) Degrees of Dissociation of HSO4− Ion in Aqueous NH4HSO4

Model II: Data for Aqueous H⁺ - NH₄⁺ - SO₄²⁻

(11) Degrees of Dissociation of HSO4⁻ Ion in Aqueous NH4HSO4