H + C2H3 (+M) -> C2H4 (+M)

k_inf = 6.08E+12 T^0.27 exp(-280 cal/mol /RT) cm3/mol s

F_cent = (1-0.782) exp(-T/207.5) + 0.782 exp(-T/2663) + exp(-6095/T)

Third-body efficiencies:

N2                    1.0 
H2     Enhanced by    2.0 
H2O    Enhanced by    6.0 
CH4    Enhanced by    2.0 
CO     Enhanced by    1.5 
CO2    Enhanced by    2.0 
C2H6   Enhanced by    3.0 
AR     Enhanced by    0.7 

SOURCE:

Results of a 2 channel RRKM calculation consistent with the 2000 K decomposition rates of Tanzawa and Gardiner (1980) and Just et al. (1977). [ See also 174 C2H4 (+M) -> H2 + C2H2(+M) ]

The rate expressions were computed using 2-channel RRKM theory, with no Waage-Rabinovitch factor.
Parameters for calculations:
<delta E> = 0.30 kcal/mol
The Lennard-Jones parameters: sigma (C2H4-N2) = 3.70 A, epsilon = 180 K
Active molecular K-rotor 3.5 amu-A^2, sigma = 1
Adiabatic I = 20.4, 16.9 amu-A^2; sigma = 4
v = 3105, 3069, 3019, 2990, 1623, 1444, 1342, 1055, 995, 950, 943, 825 cm^(-1)

Transition state 1     H2 + C2H2
delta-E(0 K) = 88.0 kcal/mol
Active molecular K-rotor 3.5 amu-A^2, sigma = 1
Adiabatic I+ = 20.4, 16.9 amu-A^2; sigma = 2
v = 3105, 3069, 2990, 1623, 1444, 1342, 1055, 995, 950 ,943, 825 cm^(-1)

Transition state 2     H + C2H3
delta-E(0 K) = 109.7 kcal/mol
Active molecular K-rotor 3.5 amu-A^2, sigma = 1
Adiabatic I+ = 25.0, 25.0 amu-A^2, sigma = 2
v = 3265, 3190, 3115, 1670, 1445, 1185, 920, 825, 785 cm^(-1)
Hindered 2-D rotor I = 1.7 amu-A^2 (90%), sigma = 1

COMMENTS:

The calculated k_o value for this decomposition channel at 2000 K in Ar of 1.0E7 cm3/mol s agrees with measurements of 1.1E7 cm3/mol s (Tanzawa and Gardiner 1980) and 0.8E7 cm3/mol s (Just et al. 1977).

The pressure broadening is expressed in the Troe form.

REFERENCES:

Just et al. (1977)

Just, T., Roth, P., and Damm, R. (1977) 16th Symposium (International) on Combustion, p. 961.

Tanzawa and Gardiner (1980)

Tanzawa, T., and Gardiner, W.C. (1980) Combust. Flame 39, 241.

                        PRESSURE = 0.1 atm N2  
______________________________________________________________________
    Temp      delta-S     delta-H      kf          kr         Keq     
     (K)    (cal/mol K)  (kcal/mol) ----(mol,cm3,s)-----   (cm3/mol)  
______________________________________________________________________
                                                                      
     300       -30.9      -111.2    3.72E+12    8.50E-67    4.38E+78
     500       -33.2      -112.1    3.11E+12    1.39E-34    2.23E+46
    1000       -35.0      -113.4    6.64E+11    6.26E-11    1.06E+22
    1500       -35.5      -113.8    1.65E+11    1.95E-03    8.46E+13
    2000       -35.5      -113.9    5.44E+10    6.78E+00    8.02E+09
    2500       -35.5      -113.8    2.20E+10    6.77E+02    3.25E+07
    3000       -35.4      -113.6    1.03E+10    1.20E+04    8.60E+05
______________________________________________________________________


                        PRESSURE = 1 atm N2    
______________________________________________________________________
    Temp      delta-S     delta-H      kf          kr         Keq     
     (K)    (cal/mol K)  (kcal/mol) ----(mol,cm3,s)-----   (cm3/mol)  
______________________________________________________________________
                                                                      
     300       -30.9      -111.2    1.04E+13    2.38E-66    4.38E+78
     500       -33.2      -112.1    1.07E+13    4.80E-34    2.23E+46
    1000       -35.0      -113.4    4.46E+12    4.21E-10    1.06E+22
    1500       -35.5      -113.8    1.36E+12    1.61E-02    8.46E+13
    2000       -35.5      -113.9    4.77E+11    5.95E+01    8.02E+09
    2500       -35.5      -113.8    1.99E+11    6.13E+03    3.25E+07
    3000       -35.4      -113.6    9.52E+10    1.11E+05    8.60E+05
______________________________________________________________________


                        PRESSURE = 10 atm N2   
______________________________________________________________________
    Temp      delta-S     delta-H      kf          kr         Keq     
     (K)    (cal/mol K)  (kcal/mol) ----(mol,cm3,s)-----   (cm3/mol)  
______________________________________________________________________
                                                                      
     300       -30.9      -111.2    1.59E+13    3.64E-66    4.38E+78
     500       -33.2      -112.1    1.97E+13    8.84E-34    2.23E+46
    1000       -35.0      -113.4    1.34E+13    1.26E-09    1.06E+22
    1500       -35.5      -113.8    6.89E+12    8.15E-02    8.46E+13
    2000       -35.5      -113.9    3.24E+12    4.04E+02    8.02E+09
    2500       -35.5      -113.8    1.55E+12    4.76E+04    3.25E+07
    3000       -35.4      -113.6    7.95E+11    9.24E+05    8.60E+05
______________________________________________________________________