Consider one of the chain branching steps found in most hydrogen-oxidation mechanisms O+HO OH+OH (Note: this...

Transcribed Image Text:

Consider one of the chain branching steps found in most hydrogen-oxidation mechanisms O+H₂O →OH+OH (Note: this reaction was not included in the smaller, simpler mechanism we used in class to explain the presence of three pressure limits for H2-O2 explosions.) a) Table 4.1 in Turns provides recommend parameters for a modified Arrhenius rate constant for this reaction. In another H2-02 kinetic mechanism (H2_Updated_Model.zip, see chem.inp.inp) developed by Prof. Dryer's group at Princeton University, another set of parameters are provided for the reverse reaction. They recommend: A (cm³/mol.s) 3.34x104 b 2.42 EA (cal/mol) -1.93x10³ Determine whether these two sets of recommended rate constant parameters satisfy the equilibrium requirement. You can use the data in Appendix A of Turns to provide the necessary equilibrium properties. Make your comparison at two temperatures: 700 K and 1800 K. Also please note that the two sources use different units for the activation energies. b) Estimate the time constant for this (forward) reaction (in Turn's wording, based on the least abundant reactant), if the gas conditions are: T(K) P (atm) XH₂O XOH 1800 K 2 Xo 0.18 0.5% 300 ppm c) For the conditions listed in part b), which is faster, the forward or reverse reaction. Consider one of the chain branching steps found in most hydrogen-oxidation mechanisms O+H₂O →OH+OH (Note: this reaction was not included in the smaller, simpler mechanism we used in class to explain the presence of three pressure limits for H2-O2 explosions.) a) Table 4.1 in Turns provides recommend parameters for a modified Arrhenius rate constant for this reaction. In another H2-02 kinetic mechanism (H2_Updated_Model.zip, see chem.inp.inp) developed by Prof. Dryer's group at Princeton University, another set of parameters are provided for the reverse reaction. They recommend: A (cm³/mol.s) 3.34x104 b 2.42 EA (cal/mol) -1.93x10³ Determine whether these two sets of recommended rate constant parameters satisfy the equilibrium requirement. You can use the data in Appendix A of Turns to provide the necessary equilibrium properties. Make your comparison at two temperatures: 700 K and 1800 K. Also please note that the two sources use different units for the activation energies. b) Estimate the time constant for this (forward) reaction (in Turn's wording, based on the least abundant reactant), if the gas conditions are: T(K) P (atm) XH₂O XOH 1800 K 2 Xo 0.18 0.5% 300 ppm c) For the conditions listed in part b), which is faster, the forward or reverse reaction.

Answer rating: 100% (QA)

Answer To determine whether the two sets of recommended rate constant parameters satisfy the equilibrium requirement we need to compare the equilibrium constant K calculated using the Arrhenius parame... View the full answer