1. The problem statement, all variables and given/known data An engine is operated slightly fuel rich (phi>1). Ethylene (C2H4) and inert nitrogen (N2) are the reactants and there are 40 mol of nitrogen for every mol of ethylene. The hydrocarbons are burned over a catalyst and converted to carbon dioxide (CO2) and water vapor (H20) only. Ambient air at 298 K with a composition of 1 mol of oxygen to 4 mol of nitrogen (O2 + 4N2) is injected before the catalyst. The catalyst is maintained at 1000 K. The temperature before the injection of the catalyst is 400 K. Calculate moles of air to moles of ethylene. 2. Relevant equations C2H4 + 40 N2 + (a/phi) (O2 + 4N2) --> b CO2 + c H20 (gas) + d N2, where phi is the equivalence ratio and a, b, c, and d are stoichiometric coefficients Hr = Hp 3. The attempt at a solution For the equation I have written in (2), should O2 be included in the products? Should N2 be included in the products? I think if I can write the equation correctly, I know how to use mass balance and Hr = Hp to solve for the stoichiometric coefficient of air. So my major question is, is my chemical equation right? If not, how do I correct it?