# Ihings to watch.out.for Make sure the AHA for the compound for the state that is reauired...

###### Question:

Ihings to watch.out.for Make sure the AHA for the compound for the state that is reauired by the problem. The phase, a reactant must be specified in the reaction Remember that elements in their standard state have a &HA O How come the two reactions below have different values of AH CsHelg)+S0 le)->3CO ,(e)+4H,O (g) AH-2043k write down the correct AH" values mol -393.5 k +90 k 0 k multiply by stoichiometric coefficients mol mol mol sum products and reactants se subtract AH" prod - AH reac 2) Calculate the enthalpy of the following reaction. Is this reaction exothermic? 2 NOCI (g) 2 NO (g) + Cl2 (g) AH (kJ/mol) NOCI 51.7 NO 90.3