H + H + M -> H2 + M

Third-body efficiencies:

N2                    1.0 
CH4    Enhanced by    2.0  
C2H6   Enhanced by    3.0 
AR     Enhanced by    0.63

SOURCE:

Warnatz, J. (1984) in Combustion Chemistry, W.C. Gardiner, Ed., Springer-Verlag, Chap. 5.
The third-body efficiency coefficient for Ar is from Warnatz (1984); the CH4 and C2H6 values are our estimates.

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    Temp      delta-S     delta-H      kf          kr         Keq
     (K)    (cal/mol K)  (kcal/mol) ----(mol,cm3,s)-----   (cm3/mol)
______________________________________________________________________

     300       -23.6      -104.2    3.33E+15    2.39E-60    1.40E+75
     500       -25.1      -104.8    2.00E+15    2.36E-30    8.48E+44
    1000       -27.1      -106.2    1.00E+15    6.28E-08    1.59E+22
    1500       -28.1      -107.5    6.67E+14    1.68E+00    3.97E+14
    2000       -28.7      -108.5    5.00E+14    8.07E+03    6.20E+10
    2500       -29.1      -109.2    4.00E+14    1.23E+06    3.24E+08
    3000       -29.3      -109.8    3.33E+14    3.38E+07    9.86E+06
______________________________________________________________________