1. Given the data. N2(g) + O2(g) = 2 NO(g) ΔH = +180.7 kJ; 2 NO(g) + O2(g) = 2 NO2(g) ΔH = −113.1 kJ; 2 N2O(g) = 2 N2(g) + O2(g) ΔH = − 163.2 kJ; Use Hess’s Law to calculate ΔH for the reaction

N2O(g) + NO2(g) = 3 NO(g); Show your work.

2. Calcium carbide (CaC2) reacts with water to form acetylene (C2H2) and Ca(OH)2. From the following enthalpy of reaction data and data in Appendix C in textbook, calculate ΔHf° for CaC2(s): CaC2(s) + 2 H2O(l) Ca(OH)2(s) + C2H2 (g) ΔH = −127.2kJ

3. Using average bond enthalpies, predict which of the following reactions will be most exothermic: a) C(g) + 2 F2(g) CF4(g) b) CO(g) +3 F2(g) CF4(g) + OF2(g) c) CO2(g) + 4 F2(g) CF4(g) + 2 OF2(g)