Question

Calculate the enthalpy for the following reaction: N2 + O2 → 2 NO given the following bond dissociation energies: N2 = 226 kcal/mol, O2 = 199 kcal/mol and NO = 145 kcal/mol.

Answer 1

The total enthalpy of the reaction is equal to the difference between the sum of the enthalpies of the products multiplied by their respective coefficients and the sum of the enthalpies of the reactants multiplied by their respective coefficients. In this case, the equation becomes 2*145 kcal/mol - 226 kcal/mol - 199 kcal/mol. This is equal to -135 kcal/ mol. This is an exothermic rxn