Aqueous H₂SO₄: Enthalpies

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.

Two further studies have been made since the work of Clegg and Brimblecombe (1995):

• S. H. Kim and M. Roth (2001) J. Chem. Eng. Data 46, 138-143.
• P. Rutten, S. H. Kim, and M. Roth (1998) Fluid Phase Equilibria 153, 317-340.

Data from these two studies are listed here.

1.  Partial Specific Heat Contents of Water and Heats of Dilution of Aqueous Sulphuric Acid

     Aav         ΔA      -L1            m1           m2           ΔHdil         t   Series    ref.  
   0.212535   0.0439743  413.9           -            -            -            25     1       a
   0.255728   0.0424010  409.0           -            -            -            25     1       a
   0.299321   0.0448262  402.8           -            -            -            25     1       a
   0.343416   0.0433029  396.7           -            -            -            25     1       a
   0.386308   0.0426515  391.2           -            -            -            25     1       a
   0.430102   0.0448763  384.3           -            -            -            25     1       a
   0.474497   0.0439743  378.2           -            -            -            25     1       a
   0.517690   0.0423008  371.4           -            -            -            25     1       a
   0.561383   0.0451970  363.9           -            -            -            25     1       a
   0.606179   0.0443051  356.0           -            -            -            25     1       a
   0.649573   0.0424010  347.5           -            -            -            25     1       a
   0.691062   0.0405771  340.5           -            -            -            25     1       a
   0.733753   0.0449765  331.6           -            -            -            25     1       a
   0.778249   0.0438240  321.0           -            -            -            25     1       a
   0.823245   0.0462392  310.5           -            -            -            25     1       a
   0.871048   0.0493258  298.9           -            -            -            25     1       a
   0.919452   0.0474819  287.3           -            -            -            25     1       a
   0.966553   0.0467303  273.9           -            -            -            25     1       a
   1.01185    0.0438441  264.6           -            -            -            25     1       a
   1.05745    0.0474718  253.5           -            -            -            25     1       a
   1.10455    0.0467603  242.0           -            -            -            25     1       a
   1.15165    0.0472714  232.0           -            -            -            25     1       a
   1.20206    0.0536451  221.4           -            -            -            25     1       a
   1.26008    0.0623638  210.3           -            -            -            25     1       a
   1.32452    0.0665227  199.31          -            -            -            25     1       a
   1.39447    0.0733474  187.77      40.88168     38.78646      -248.105        25     1       a
   1.47835    0.0944426  175.97      38.78687     36.38571      -299.392        25     1       a
   1.56864    0.0862751  164.78      36.38735     34.43962      -256.108        25     1       a
   1.66325    0.102861   154.49      34.43872     32.37279      -286.272        25     1       a
   1.76747    0.105637   144.31      32.37334     30.49462      -274.625        25     1       a
   1.88182    0.122874   134.77      30.49303     28.56493      -298.313        25     1       a
   2.01149    0.136683   125.21      28.56652     26.68918      -308.302        25     1       a
   2.15651    0.153169   115.70      26.68797     24.85743      -319.250        25     1       a
   2.32417    0.182241   106.67      24.85805     22.98242      -350.194        25     1       a
   2.51407    0.197514    97.01      22.98211     21.24481      -345.175        25     1       a
  -0.12846    0.01591    952.3           -            -            -            25     2       a
  -0.11155    0.01791    953.3           -            -            -            25     2       a
  -0.09508    0.01503    954.0           -            -            -            25     2       a
  -0.07819    0.01875    954.3           -            -            -            25     2       a
  -0.05991    0.01781    954.0           -            -            -            25     2       a
  -0.04252    0.01696    954.7           -            -            -            25     2       a
  -0.02546    0.01717    956.1           -            -            -            25     2       a
  -0.00833    0.00263    943.0           -            -            -            25     3       a
  -0.00604    0.00193    947.0           -            -            -            25     3       a
  -0.00393    0.00230    942.0           -            -            -            25     3       a
  -0.00180    0.00197    927.0           -            -            -            25     3       a
   0.00026    0.00215    866.0           -            -            -            25     3       a
   0.00257    0.00246    695.0           -            -            -            25     3       a
   0.00494    0.00227    541.0           -            -            -            25     3       a
   0.02508    0.03802    446.6           -            -            -            25     3       a
   0.05972    0.03125    435.1           -            -            -            25     3       a
   0.09356    0.03643    430.5           -            -            -            25     3       a
   0.12968    0.03581    425.8           -            -            -            25     3       a
   0.16512    0.03499    420.6           -            -            -            25     3       a
   0.20132    0.03749    415.9           -            -            -            25     3       a
   0.23842    0.03665    411.2           -            -            -            25     3       a
   2.6121     0.3540      92.94      22.79537     19.90212      -592.702        25     4       a
   3.0151     0.4520      78.56      19.90212     17.12659      -639.670        25     4       a
   3.5368     0.5913      64.69      17.12633     14.48395      -689.042        25     4       a
   4.3712     1.0775      49.66      14.48395     11.30541      -963.932        25     4       a
   5.5870     1.3541      35.74      11.30541      8.861519     -871.770        25     4       a
   7.9086     3.2891      21.07       8.861519     5.810544    -1248.213        25     4       a
  11.989      4.8712       9.07       5.810392     3.848217     -795.954        25     4       a
  17.907      6.965        3.35       3.848244     2.595151     -420.338        25     4       a
  26.111      9.440        1.24       2.594969     1.800428     -210.880        25     4       a
  15.143      5.204        5.00       4.426202     3.128148     -468.776        25     5       a
  21.869      8.247        1.98       3.128060     2.135577     -294.170        25     5       a
  31.398     10.812        0.78       2.135618     1.508232     -151.909        25     5       a
  45.083     16.558        0.36       1.508232     1.040234     -107.379        25     5       a
  64.892     23.06         0.20       1.040234     0.726348      -83.085        25     5       a
  93.015     33.19         0.11       0.726369     0.506422      -65.769        25     5       a
 133.41      47.60         0.06       0.506422     0.353088      -51.456        25     5       a
   1.9599     0.3223     160.8       30.85959     26.17038      -669.089       -20     6       a
   2.2462     0.2504     144.6       26.171       23.40756      -446.748       -20     6       a
   2.5965     0.4502     129.8       23.40756     19.67277      -683.184       -20     6       a
   3.0436     0.4440     115.3       19.67277     16.998        -557.793       -20     6       a
   3.5926     0.6540     102.9       16.998       14.16182      -675.519       -20     6       a
   4.2628     0.6864      92.1       14.16182     12.05139      -575.430       -20     6       a
   5.1317     1.0513      83.0       12.05125      9.81178      -708.997       -20     6       a
   6.3908     1.4669      74.0        9.81178      7.79151      -751.440       -20     6       a
   8.1314     2.0143      65.8        7.79151      6.07412      -734.291       -20     6       a
  10.7250     3.1721      56.4        6.07386      4.50885      -619.182       -20     6       a

Notes and References

• Key: Aav - average composition, which is equal to (moles of H2O) / (moles of H2SO4) for Aav ≥ 0.0, and (moles of H2O - moles of SO3) / (moles of SO3) for Aav < 0.0; ΔA - the change in A from the initial solution concentration to the final one after dilution; L1 - the partial specific heat content of water, in defined calories per gram; m1 - initial molality (calculated for solutions of about 40 mol kg^-1 or less only); m2 - final molality; ΔHdil - heat of dilution (cal mol^-1) which is related to L1 by: ΔHdil = ΔA × L1 × MW, where MW is the molar mass of water in grams; t - experimental temperature (^oC); ref. - source of data.
• Source: a - J. E. Kunzler and W. F. Giauque (1952) J. Amer. Chem. Soc. 74, 3472-3476, corrected as given by W. F. Giauque et al. (1960) J. Amer. Chem. Soc. 82, 62-70.
• 1 calorie is defined as 4.1833 international joules, the molar mass of H2SO4 was 98.082 g, and the molar mass of water 18.0160 g. To convert values in calories to J, multiply L1 by the factor (4.1833 × 1.000165). The values of ΔHdil above, which were used by Clegg and Brimblecombe (1994), were converted using MW = 18.015 g.
• Molalities and heats of dilution are only listed for values of m1 less than about 40 mol kg^-1, which is the upper limit of concentration to which the model of Clegg and Brimblecombe was fitted. The tabulated L1 at 253.15 K are based upon H₁^o = 0 at 298.15 K, and were adjusted by adding 820.86 cal mol^-1 (or about 45.565 cal g^-1) to L1 in order to calculate ΔHdil at the lower temperature.

2.  Heats of Dilution of Aqueous Sulphuric Acid at 25 ^oC

  √m1        √m2           m1           m2          ΔHdil      T      ref.   
0.031705  0.030134      1.00521E-3   9.08058E-4    -52.85    298.15    a 
0.033214  0.031637      1.10317E-3   1.00090E-3    -50.71    298.15    a    
0.0404839 0.038529      1.63895E-3   1.48448E-3    -66.61    298.15    a    
0.0410509 0.039057      1.68518E-3   1.52545E-3    -65.49    298.15    a    
0.056369  0.053568      3.17746E-3   2.86953E-3    -83.86    298.15    a    
0.056548  0.053796      3.19768E-3   2.89401E-3    -78.62    298.15    a    
0.095864  0.091232      9.18991E-3   8.32328E-3    -93.33    298.15    a    
0.10000   0.095259      1.00000E-2   9.07428E-3    -93.38    298.15    a    
0.21840   0.20680       4.76986E-2   4.27662E-2    -83.67    298.15    a    
0.25180   0.23839       6.34032E-2   5.68298E-2    -77.97    298.15    a    
0.25180   0.23875       6.34032E-2   5.70016E-2    -73.08    298.15    a    
0.37394   0.35398       1.39831E-1   1.25302E-1    -61.78    298.15    a    
0.37900   0.35948       1.43641E-1   1.29226E-1    -58.88    298.15    a    
0.37900   0.35989       1.43641E-1   1.29521E-1    -57.97    298.15    a    
0.38659   0.366721      1.49452E-1   1.34484E-1    -57.35    298.15    a    
0.42253   0.40030       1.78532E-1   1.60240E-1    -53.42    298.15    a    
0.42253   0.40145       1.78532E-1   1.61162E-1    -50.40    298.15    a    
0.47311   0.44907       2.23833E-1   2.01664E-1    -48.02    298.15    a    
0.47311   0.44985       2.23833E-1   2.02365E-1    -45.78    298.15    a    
0.50564   0.48041       2.55672E-1   2.30794E-1    -44.78    298.15    a    
0.62997   0.59868       3.96862E-1   3.58418E-1    -35.60    298.15    a    
0.71542   0.68034       5.11826E-1   4.62863E-1    -31.73    298.15    a    
1.0934    1.0328        1.19552      1.06668       -35.26    298.15    a    
1.0934    1.0349        1.19552      1.07102       -34.04    298.15    a    
2.5344    2.3640        6.42318      5.58850      -352.88    298.15    a    

Notes and References

• Key: m1 - initial molality of the aqueous H2SO4 (before dilution); m2 - the final molality (after dilution); ΔHdil - the heat of dilution in cal mol^-1; T - temperature (K); ref. - source.
• Source: a - Y. C. Wu and T. F. Young (1980) J. Res. Nat. Bur. Standards 85, 11-17.
• Values of the square roots of m1 and m2, given above, are listed by Wu and Young and the molalities m1 and m2 have been calculated from them.

3.  Heats of Dilution of Aqueous Sulphuric Acid at 298.15 K

        m1           m2        ΔHdil     error     T       ref.  weight
    5.02319E-2   7.34490E-4    -3410      14.8   298.15     a     1.0 
    5.02319E-2   1.45838E-3    -3048       9.2   298.15     a     1.0        
    5.02319E-2   2.17057E-3    -2770      12     298.15     a     1.0        
    2.50949E-2   3.67191E-4    -3086       3     298.15     a     0.0                       
    2.50949E-2   7.29074E-4    -2836       3.5   298.15     a     0.0                       
    1.25422E-2   1.83644E-4    -2623      14     298.15     a     1.0                       
    1.25422E-2   3.64583E-4    -2452      10     298.15     a     0.0                       
    6.26983E-3   9.18019E-5    -2055     110     298.15     a     1.0                       
    6.26983E-3   1.82240E-4    -1936      60     298.15     a     0.0                       
    3.13459E-3   4.59059E-5    -1711      49     298.15     a     0.0                       
    3.13459E-3   9.11299E-5    -1517      38     298.15     a     0.0                       

Notes and References

• Key: m1 - initial molality of the aqueous H2SO4 (before dilution); m2 - the final molality (after dilution); ΔHdil - the heat of dilution in cal mol^-1; error - uncertainty (cal mol^-1) in ΔHdil; T - temperature (K); ref. - source; weight - a value of zero indicates that the point was excluded from the fits carried out by Clegg and Brimblecombe (1994).
• Source: a - E. Lange, J. Monheim and A. L. Robinson (1933) J. Amer. Chem. Soc. 55, 4733-4744.
• Values of the m1 and m2, given above, and listed in Table I of Lange et al., were calculated from tabulated mol per litre concentrations using densities from the compilation of Sohnel and Novotny [O. Sohnel and P. Novotny (1985) Densities of Aqueous Solutions of Inorganic Substances, Amsterdam, Elsevier]. Exothermic mixing implies a negative sign for ΔHdil, and the values of ΔHdil from Lange et al. have been changed to reflect this.

4.  Heats of Dilution of Aqueous Sulphuric Acid at Approximately 25 ^oC

      m1           m2        ΔHdil        t       ref.  weight
  0.00305200   0.00276501   -104.30     24.920      a    0.0
  0.00504464   0.00456456   -100.55     25.043      a    0.0
  0.00507832   0.00458799   -109.75     25.064      a    0.0
  0.00668824   0.00604803    -94.163    25.025      a    1.0
  0.00674976   0.00608941   -100.77     25.041      a    1.0
  0.00813490   0.00735669   -100.38     25.021      a    1.0
  0.01026441   0.00926296   -107.47     25.027      a    1.0
  0.01104983   0.01008040    -83.061    24.968      a    1.0
  0.01284195   0.01152580   -108.93     25.039      a    1.0
  0.01631424   0.01500961    -72.859    25.006      a    1.0
  0.01739951   0.00065771  -2477.4      24.871      a    0.0
  0.01739951   0.00069799  -2587.3      24.879      a    0.0
  0.01739951   0.00158011  -2275.9      24.869      a    0.0
  0.01771930   0.01601037    -91.376    25.211      a    1.0
  0.01859996   0.01693355    -83.929    24.911      a    1.0
  0.02537360   0.02298975    -85.431    25.033      a    1.0
  0.02728059   0.02427661   -102.99     24.966      a    1.0
  0.02770755   0.02503081    -91.176    25.053      a    1.0
  0.02886691   0.02603263    -88.258    24.923      a    1.0
  0.03921862   0.03548839    -85.441    25.088      a    1.0
  0.04133185   0.03733690    -88.480    25.001      a    1.0
  0.04388671   0.03967960    -86.453    25.194      a    1.0
  0.04731603   0.04270224    -82.808    25.030      a    1.0
  0.06288085   0.05699960    -73.253    24.979      a    1.0
  0.06657916   0.06013186    -75.001    24.969      a    1.0
  0.08455444   0.07474355    -65.910    25.050      a    0.0
  0.08690072   0.07930002    -59.950    24.988      a    1.0
  0.10831520   0.09812017    -57.975    25.017      a    1.0
  0.14669985   0.13407834    -46.451    24.978      a    1.0
  0.16809961   0.15339981    -45.007    25.002      a    1.0
  0.17781345   0.16051757    -50.228    25.041      a    1.0
  0.29669930   0.26733063    -40.770    25.074      a    1.0
  0.33139616   0.29993467    -37.150    25.012      a    1.0
  0.47809789   0.43349645    -31.531    24.948      a    1.0
  0.64852621   0.58421942    -30.616    25.291      a    1.0
  0.78025920   0.69996360    -31.622    25.086      a    1.0
  0.83628864   0.75179107    -30.546    25.061      a    1.0
  0.85626919   0.77086311    -29.918    25.067      a    1.0
  1.16860229   1.04903716    -32.891    25.104      a    1.0
  1.46580300   1.31860092    -37.279    25.080      a    1.0
  1.96015983   1.84354466    -29.296    24.983      a    1.0
  2.79010564   2.73487183    -16.927    25.127      a    1.0
  2.93699433   2.75239155    -57.067    25.010      a    1.0
  2.93699433   2.75739377    -55.504    25.009      a    1.0
  3.67929221   3.27300342   -140.95     25.116      a    1.0

Notes and References

• Key: m1 - initial molality of the aqueous H2SO4 (before dilution); m2 - the final molality (after dilution); ΔHdil - the heat of dilution in cal mol^-1; T - temperature (K); ref. - source; weight - a value of zero indicates that the point was excluded from the fits carried out by Clegg and Brimblecombe (1994).
• Source: a - W. L. Groenier (1933) Ph.D Thesis, University of Chicago.
• Values of the m1 and m2, given above were calculated from tabulated square roots of the stoichiometric ionic strength (equal to SQRT(3 × m)).

5.  Heats of Dilution of Aqueous H2SO4, at Various Temperatures

  x1        x2          ΔHdil      error    t    table  ref.  
  0.1092   8.897E-2    -2553.6     32.93    10     1     a
  0.1092   7.502E-2    -4198.4     56.80    10     1     a
  0.1092   5.714E-2    -6001.7     74.75    10     1     a
  0.1092   4.615E-2    -6969.0     85.38    10     1     a
  0.1092   4.615E-2    -6818.8     82.88    10     1     a
  0.1092   3.115E-2    -7828.2     92.94    10     1     a 
  0.1092   3.115E-2    -7638.6     91.15    10     1     a 
  0.1092   1.966E-2    -8374.7     98.38    10     1     a
  0.1092   1.966E-2    -8172.2     96.36    10     1     a
  0.1092   1.271E-2    -8687.9    111.50    10     1     a
  0.1092   1.271E-2    -8654.7    111.10    10     1     a
  0.1092   1.080E-2    -8873.3    113.30    10     1     a
  0.1092   1.080E-2    -9099.2    115.50    10     1     a
  0.1092   8.818E-3    -8976.4    114.40    10     1     a
  0.1092   8.818E-3    -9202.5    116.60    10     1     a
  0.1092   6.039E-3    -9493.9    132.00    10     1     a
  0.01254  1.089E-2      -66.6      2.747   20     2     a
  0.01254  9.625E-3     -119.9      5.239   20     2     a
  0.01254  8.326E-3     -315.2      8.985   20     2     a
  0.01254  6.234E-3     -583.8     17.08    20     2     a
  0.01254  4.149E-3    -1279.3     30.42    20     2     a
  0.01254  3.554E-3    -1607.5     38.18    20     2     a
  0.01254  2.486E-3    -2269.7     49.42    20     2     a
  0.01254  2.070E-3    -2723.2     59.58    20     2     a
  0.01254  1.774E-3    -3060.8     64.59    20     2     a
  0.01254  1.461E-3    -3562.9     75.69    20     2     a
  0.01254  1.461E-3    -3513.0     74.73    20     2     a
  0.01254  1.128E-3    -4267.5     89.21    20     2     a
  0.01254  1.128E-3    -4290.2     89.65    20     2     a
  0.01254  9.191E-4    -4908.0    101.50    20     2     a
  0.01254  9.191E-4    -4929.3    101.90    20     2     a
  0.01254  5.907E-4    -6406.4    132.70    20     2     a
  0.01254  4.002E-4    -7859.8    165.50    20     2     a
  0.1092   2.473E-2    -8001.1    106.20    20     2     a
  0.1092   1.966E-2    -8353.7     98.63    20     2     a
  0.1092   1.271E-2    -8980.0    109.50    20     2     a
  0.1092   1.080E-2    -9174.0    111.70    20     2     a
  0.1092   8.818E-3    -9595.5    116.40    20     2     a
  0.1092   6.039E-3    -9755.8    123.00    20     2     a
  0.8322   6.627E-1    -9297.3     72.67    20     2     a
  0.8322   6.627E-1    -9232.4     72.17    20     2     a
  0.8322   6.627E-1    -9313.5     76.51    20     2     a
  0.8322   4.114E-1   -28213      219.5     20     2     a
  0.8322   4.114E-1   -28235      219.7     20     2     a
  0.8322   4.114E-1   -27902      224.6     20     2     a
  0.8322   3.283E-1   -34988      273.7     20     2     a
  0.8322   3.283E-1   -34745      271.9     20     2     a
  0.8322   3.283E-1   -34618      285.7     20     2     a
  0.8322   2.339E-1   -44599      347.8     20     2     a
  0.8322   2.339E-1   -42855      334.4     20     2     a
  0.8322   2.339E-1   -43122      410.5     20     2     a
  0.8322   1.634E-1   -50711      395.0     20     2     a
  0.8322   1.634E-1   -51600      402.3     20     2     a
  0.8322   1.634E-1   -51245      414.0     20     2     a
  0.8322   1.088E-1   -57439      446.9     20     2     a
  0.8322   1.088E-1   -57931      458.6     20     2     a
  0.8322   1.088E-1   -57761      464.2     20     2     a
  0.8322   7.407E-2   -63128      506.2     20     2     a
  0.8322   7.407E-2   -62621      514.2     20     2     a
  0.8322   4.401E-2   -64771      530.8     20     2     a
  1.000    8.293E-1    -6226      165.2     20     3     a
  1.000    7.240E-1   -11336      306.8     20     3     a
  1.000    5.757E-1   -20185      589.8     20     3     a
  1.000    5.540E-1   -20790      482.4     20     3     a
  1.000    5.430E-1   -23320      624.9     20     3     a
  0.1092   1.966E-2    -8454.8     99.47    40     4     a
  0.1092   1.966E-2    -8633.5     91.67    40     4     a
  0.1092   1.966E-2    -8700.0     92.34    40     4     a
  0.1092   1.271E-2    -9239.3    113.3     40     4     a
  0.1092   1.271E-2    -9022.7    110.9     40     4     a
  0.1092   1.271E-2    -9095.3     99.88    40     4     a
  0.1092   1.271E-2    -9171.7    100.6     40     4     a
  0.1092   1.080E-2    -9495.4    116.1     40     4     a
  0.8322   7.112E-1    -6205.4     78.47    40     4     a
  0.8322   6.627E-1    -9230.3    116.7     40     4     a
  0.8322   5.507E-1   -16912      213.9     40     4     a
  0.8322   4.115E-1   -27416      347.1     40     4     a
  0.8322   3.284E-1   -34732      439.3     40     4     a
  0.8322   2.340E-1   -43315      547.5     40     4     a
  0.8322   2.340E-1   -43540      550.4     40     4     a
  0.8322   1.635E-1   -51492      650.6     40     4     a
  0.8322   1.635E-1   -51082      645.4     40     4     a
  0.8322   1.088E-1   -57942      731.9     40     4     a
  0.8322   1.088E-1   -57080      721.0     40     4     a
  0.8322   4.403E-2   -64744      819.8     40     4     a
  0.8322   3.917E-1   -29515      655.4     40     5     a
  0.8322   3.309E-1   -34300      630.1     40     5     a
  0.8322   2.117E-1   -45613      679.2     40     5     a
  0.8322   1.478E-1   -52892      706.7     40     5     a
  0.8322   1.470E-1   -52888      763.6     40     5     a
  0.8322   1.447E-1   -53173      794.8     40     5     a
  0.8322   9.832E-2   -58433     1085       40     5     a
  0.8322   9.530E-2   -59452      729.1     40     5     a
  0.8322   7.391E-2   -61498      644.5     40     5     a
  0.8322   7.194E-2   -60970      842.6     40     5     a
  0.8322   3.738E-2   -64451      720.5     40     5     a
  0.8322   1.394E-2   -66524      679.1     40     5     a
  0.8322   8.264E-3   -67611      701.0     40     5     a
  0.8322   5.731E-3   -68953      701.4     40     5     a
  0.8322   5.615E-3   -69192      719.1     40     5     a
  1.000    8.797E-1    -5001.1    164.3     40     5     a
  1.000    7.516E-1   -10615      266.0     40     5     a
  1.000    5.778E-1   -20990      580.8     40     5     a
  0.8322   6.568E-1    -9518.2    302.2     60     6     a
  0.8322   5.805E-1   -14666      422.9     60     6     a
  0.8322   4.214E-1   -25220      687.6     60     6     a
  0.8322   2.858E-1   -39324      916.8     60     6     a
  0.8322   2.765E-1   -40367      940.0     60     6     a
  0.8322   1.987E-1   -49094     1117       60     6     a
  0.8322   1.695E-1   -52053      975.5     60     6     a
  0.8322   1.433E-1   -54995      929.4     60     6     a
  0.8322   1.157E-1   -56327      829.1     60     6     a
  0.8322   7.128E-2   -62442      749.7     60     6     a
  0.8322   4.184E-2   -65051      598.6     60     6     a
  0.8322   1.925E-2   -66660      515.3     60     6     a
  0.8322   9.737E-3   -68342      482.5     60     6     a
  0.8322   5.368E-3   -68731      464.4     60     6     a
  0.8322   2.574E-3   -68700      579.3     60     6     a
  1.000    7.876E-1    -9295.1    218.3     60     6     a
  1.000    5.674E-1   -21620      521.3     60     6     a
  1.000    3.610E-1   -38437      922.8     60     6     a

Notes and References

• Key: x1 - initial mole fraction of the aqueous H2SO4 (before dilution); x2 - the final mole fraction (after dilution); ΔHdil - the heat of dilution in J mol^-1; error - the maximum absolute uncertainty associated with the measurement; t - temperature (^oC); ref. - source.
• Source: a - S. H. Kim and M. Roth (2001) J. Chem. Eng. Data 46, 138-143.
• Values above were taken from a preprint of the above paper. Values of ΔHdil are negative for exothermic mixing.

6.  Heats of Dilution of Aqueous H2SO4, at Various Temperatures

   A1       A2       ΔHdil    Aerr    error  t   table  ref.
 8.1540   10.240     -2554    0.080    32    10    21    a
 8.1540   12.330     -4198    0.100    55    10    21    a
 8.1540   16.500     -6002    0.130    72    10    21    a
 8.1540   20.670     -6969    0.170    82    10    21    a
 8.1540   20.670     -6819    0.170    80    10    21    a
 8.1540   31.100     -7828    0.250    90    10    21    a
 8.1540   31.100     -7639    0.250    88    10    21    a
 8.1540   10.240     -2510    0.080    30    20    22    a
 8.1540   10.240     -2491    0.080    37    20    22    a
 8.1540   12.330     -4167    0.100    50    20    22    a
 8.1540   13.370     -4634    0.110    63    20    22    a                                               
 8.1540   16.500     -5881    0.130    69    20    22    a                                               
 8.1540   18.580     -6376    0.150    83    20    22    a                                               
 8.1540   20.670     -6806    0.170    79    20    22    a                                               
 8.1540   23.800     -7189    0.190    93    20    22    a                                               
 8.1540   29.010     -7642    0.230    98    20    22    a                                               
 8.1540   31.100     -7828    0.250    89    20    22    a                                               
 8.1540   34.220     -7785    0.270   100    20    22    a                                               
 8.1540   10.240     -2376    0.080    29    40    23    a                                               
 8.1540   10.240     -2392    0.080    26    40    23    a                                               
 8.1540   12.330     -3805    0.100    42    40    23    a                                               
 8.1540   12.330     -3803    0.100    42    40    23    a                                               
 8.1540   13.370     -4444    0.110    50    40    23    a                                               
 8.1540   16.500     -5666    0.130    60    40    23    a                                               
 8.1540   18.580     -6210    0.150    68    40    23    a                                               
 8.1540   20.670     -6633    0.170    69    40    23    a                                               
 8.1540   20.670     -6591    0.170    68    40    23    a                                               
 8.1540   23.800     -7022    0.190    77    40    23    a                                               
 8.1540   23.800     -7107    0.190    80    40    23    a                                               
 8.1540   29.010     -7568    0.230    83    40    23    a                                               
 8.1540   29.010     -7662    0.250    90    40    23    a                                               
 8.1540   31.100     -7757    0.250    80    40    23    a                                               
 8.1540   31.100     -7785    0.250    80    40    23    a                                               

Notes and References

• Key: A1 - initial concentration of the aqueous H2SO4 (before dilution) in moles of water per mole of acid; A2 - the final concentration (after dilution) in moles of water per mole of acid; ΔHdil - the heat of dilution in J mol^-1; Aerr - the maximum absolute uncertainty associated with concentration A2 in moles of water per mole of acid; error - the maximum absolute uncertainty associated with ΔHdil (J mol^-1); t - temperature (^oC); ref. - source of data.
• Source: a - P. Rutten, S. H. Kim, and M. Roth (1998) Fluid Phase Equilibria 153, 317-340.
• The maximum absolute uncertainty associated with concentration A1 is 0.065 moles of water per mole of acid for all the solutions listed.