Question

Even the oxidation of carbon monoxide (which could be used industrially to remove this toxic gas) can be explosive under certain conditions. A simplified mechanism for CO combustion can be considered to be:

                                                                                                                          equation #

                              CO (g) + O₂ (g)    →    CO₂ (g) + O: (g)                             1                   

                            O: (g) + CO (g)   →     CO₂* (g)                                        2

                           CO₂* (g) + O₂ (g)   →     CO₂ (g) + 2O: (g)                        3

                                          CO₂* (g)     →     CO₂ (“deactivated” by wall)           4

                              CO₂* (g) + M (g) →     CO₂ (g) +   M (g)                         5

           

            Both CO₂* (an “activated form of CO₂) and O: (a “di-radical”) should be regarded as highly reactive intermediates (“active centers”). Derive a rate expression that will explain the explosive behavior of this system. Discuss why the “first” and “second” explosive limits can occur by indicating the relative importance of the terms in your expression.

Answer 1