Oxalic Acid Data

The tables of data for the pure aqueous acid are given below.

(1a) Water Activities from Electrodynamic Balance Measurements

  aW(orig.)  mfs(orig.)   aW(adj.)  mass(adj.)  mfs(adj.)   m(adj.)  np   t   uncert.(a) uncert.(b)  ref.  weight
   0.8922     0.2811       0.9022     1.181       0.3319     5.52    1e  25.0   0.01      0.05        a      -   
   0.8500     0.3640       0.8600     1.156       0.4207     8.07    1e  25.0   0.01      0.06        a      -   
   0.7947     0.4878       0.8047     1.123       0.5478    13.46    1e  25.0   0.01      0.06        a      -   
   0.8516     0.3640       0.8616     1.157       0.4210     8.08    1e  25.0   0.01      0.06        a      -   
   0.7428     0.5702       0.7528     1.092       0.6228    18.34    1e  25.0   0.01      0.05        a      -   
   0.6764     0.6836       0.6864     1.053       0.7199    28.54    1e  25.0   0.01      0.04        a      -   
   0.8516     0.3640       0.8616     1.157       0.4210     8.08    1e  25.0   0.01      0.06        a      -   
   0.5964     0.7734       0.6064     1.006       0.7778    38.89    1e  25.0   0.01      0.004       a      -   
   0.5146     1.0          0.5246       -           -         -      1e  25.0   0.01       -          a      -   
   0.0440     1.0          0.0540       -           -         -      1e  25.0   0.01       -          a      -   
   0.3542     0.9944       0.3642       -           -         -      1g  25.0   0.01       -          a      -   
   0.6587     0.9972       0.6687       -           -         -      1g  25.0   0.01       -          a      -   
   0.9086     0.8525       0.9186       -           -         -      1g  25.0   0.01       -          a      -   
   0.9251     0.1963       0.9351     1.200       0.2356     3.42    2e  25.0   0.01      0.04        a      -   
   0.8265     0.4194       0.8365     1.142       0.4789    10.21    2e  25.0   0.01      0.06        a      -   
   0.6352     0.7393       0.6452     1.029       0.7605    35.27    2e  25.0   0.01      0.02        a      -   
   0.8605     0.3386       0.8705     1.162       0.3934     7.20    3e  25.0   0.01      0.05        a      -   
   0.7023     0.6056       0.7123     1.068       0.6470    20.36    3e  25.0   0.01      0.04        a      -   
   0.5667     0.8252       0.5767     1.000       0.8252    52.43    3e  25.0   0.01      0.01        a      -   
   0.5179     0.9909       0.5279       -           -         -      3e  25.0   0.01       -          a      -   
   0.0580     1.00         0.0680       -           -         -      3e  25.0   0.01       -          a      -   
   0.5314     0.9524       0.5414       -           -         -      3g  25.0   0.01       -          a      -   
   0.7900     0.9341       0.8000       -           -         -      3g  25.0   0.01       -          a      -   
   0.8605     0.9312       0.8705       -           -         -      3g  25.0   0.01       -          a      -   
   0.9141     0.8660       0.9241       -           -         -      3g  25.0   0.01       -          a      -   
   0.9426     0.8582       0.9526       -           -         -      3g  25.0   0.01       -          a      -

Notes and References

Symbols: aW(orig.) - water activity as given by Peng et al. (2001), and at http://ihome.ust.hk/~keckchan/hygroscopic.htmlY; mfs(orig.) - mass fraction of solute in the particle, as given by Peng et al. (2001); aW(adj.) - adjusted water activity, equal to aW(orig.) + 0.010; mass(adj.) - mass of solute in the aqueous suspended particles, normalised to a value of 1.0 at aW(orig.) = 0.5179, and adjusted for posible evaporative loss of oxalic acid from the particle; mfs(adj.) - mass fraction of solute in aqueous particles, based on mass(adj.) and a total particle mass equal to 1.0/mfs(orig.); m(adj.) - solute molality in the particle (only for those particles that appear to be fully aqueous and contain no solid); np - particle number (suffix e indicates an evaporation experiment in an atmosphere of decreasing relative humidity, and g particle growth in an atmosphere of increasing relative humidity); t - experimental temperature (^oC); uncert.(a) and uncert.(b) - see note below; ref. - source of data; weight - the weight assigned in the fit of the model to determine parameter values. All values are blank (" - "), as Raoult's law was assumed in the study of Clegg and Seinfeld (2006).
The uncertainty in the relative humidity determination (aW) in the experiments is ±0.01 [uncert.(a)], and for mfs it is generally about ±0.01. However, this figure does not take into account the uncertainty associated with the adjustment to mfs that has been made here. We have assigned an uncertainty to the mfs(adj.) values [uncert.(b)] equal to the greater of ±0.01 and ±[mfs(orig.) - mfs(adj.)].
Source: a - C. Peng, M. N. Chan and C. K. Chan (2001) Environ. Sci. Technol. 35, 4495-4501.

(1b) Osmotic Coefficients and Water Activities from Bulk Solution Measurements

   nS/nW       aW         m        osm       t     uncert.   ref.  weight   
     -          -      0.2001    2.2279     25.0   0.84(a)    a      -   
     -          -      0.3969    1.5471     25.0   0.42(a)    a      -   
     -          -      0.7039    1.2720     25.0   0.24(a)    a      -   
     -          -      0.9265    1.2104     25.0   0.18(a)    a      -   
     -          -      1.2478    0.9896     25.0   0.14(a)    b      -   
     -          -      1.208     1.022      25.0   0.14(a)    c      -   
     -          -      0.2306    1.9335     25.0   0.73(a)    d      -   
     -          -      0.4644    1.3220     25.0   0.36(a)    d      -   
     -          -      0.7094    1.2621     25.0   0.24(a)    d      -   
     -          -      0.9676    1.1590     25.0   0.18(a)    d      -   
     -          -      1.2346    1.1383     25.0   0.14(a)    d      -   
  0.025237   0.9714      -         -        25.0   0.009(b)   e      -   
  0.025237   0.9716      -         -        25.0   0.009(b)   e      -   
  0.025237   0.9699      -         -        25.0   0.009(b)   e      -   
  0.020343   0.9834      -         -        25.0   0.009(b)   e      -   
  0.014836   0.9802      -         -        25.0   0.009(b)   e      -   
  0.011689   0.9819      -         -        25.0   0.009(b)   e      -   
  0.008168   0.9823      -         -        25.0   0.009(b)   e      -   
  0.020048   0.9751      -         -        25.0   0.009(b)   e      -   
  0.010295   0.9790      -         -        25.0   0.009(b)   e      -   
  0.010115   0.9762      -         -        25.0   0.009(b)   e      -   
     -       0.979     0.849       -        25.0   0.007(c)   f      -   
     -       0.976     1.331       -        25.0   0.005(c)   f      -   
     -       0.9675    1.853       -        25.0   0.004(c)   f      -   
     -          -      0.436     1.472      25.0   0.13(d)    g      -   
     -          -      0.572     1.360      25.0   0.098(d)   g      -   
     -          -      0.626     1.387      25.0   0.090(d)   g      -   
     -          -      0.760     1.339      25.0   0.074(d)   g      -   
     -          -      0.887     1.330      25.0   0.064(d)   g      -   
     -          -      1.062     1.301      25.0   0.054(d)   g      -   
     -          -      1.125     1.294      25.0   0.051(d)   g      -

Notes and References

Symbols: nS/nW - moles of solute per mole of water in the aqueous solution; aW - water activity; m - molality; osm - molal osmotic coefficient; t - experimental temperature (^oC); uncert. - uncertainty in the osmotic coefficient; ref. - source of data; weight - the weight assigned in the fit of the model to determine parameter values. All values are blank (" - "), as Raoult's law was assumed in the study of Clegg and Seinfeld (2006).
The original data of Wise et al. (2003), which are not tabulated in their paper, were obtained directly from the authors. The values of Braban et al. (2003) were read from their Figure 4.
Source: a - C. Peng, M. N. Chan and C. K. Chan (2001) Environ. Sci. Technol. 35, 4495-4501; b - C. Marcolli, B. P. Luo and Th. Peter (2004) J. Phys. Chem. A, 108, 2216-2224; c - as for b, but using the oxalic solubility given in the compilation: Stephen, H. and Stephen, T. Solubilities of Inorganic and Organic Compounds; Pergamon: Oxford, 1979; Vol. 1.; d - M. C. Maffia and A. J. A. Meirelles (2001) J. Chem. Eng. Data 46, 582-587; e - M. E. Wise, J. D. Surratt, D. B. Curtis, J. E. Shilling and M. A. Tolbert (2003) J. Geophys. 108, doi:10.1029/2003JD003775, 8 pages; f - C. F. Braban, M. F. Carrol, S. A. Styler and J. P. D. Abbatt (2003) J. Phys. Chem. A, 107, 6594-6602; g - T. Kirsch and G. Maurer (1996) Ind. Eng. Chem. 35, 1722-1735.
Uncertainties: (a) in the listed osmotic coefficient, based upon ±0.003 in the measured water activity aW; (b) in the measured water activity (average of the 0.5% to 1.35% in RH given by Wise et al.; (c) in the measured water activity, given as error bars in Figure 4 of Braban et al. (2003); (d) in the listed osmotic coefficient, based upon ±0.001 in the measured water activity aW.