H + Enthalpy C—H H AHo heat released or absorbed during a chemical reaction at standard conditions EXothermic, (-AR, heat is released Endothermic, (+AR), heat is absorbed Reactions favor products with lowest enthalpy(strongest bonds) Chapter 4Chapter 4 14 Enthalpy • DHo = heat released or absorbed during a chemical reaction at standard conditions. • Exothermic, (-DH), heat is released. • Endothermic, (+DH), heat is absorbed. • Reactions favor products with lowest enthalpy (strongest bonds). =>