What you’ll learn5 learning objectivesChoose one objective for a focused lesson, or study the complete topic.1.2.1Bond energies• Bond-breaking absorbs energy• Bond-forming releases energy• Calculate enthalpy change from average bond enthalpiesSyllabus objective1.2.2Hess's law• Enthalpy change independent of pathway• Apply Hess's law to multistep reaction cyclesSyllabus objective1.2.3(HL)—Standard enthalpy changes• Combustion: ΔHc⦵• Formation: ΔHf⦵• Deduce equations and solve problems using standard enthalpy dataSyllabus objective1.2.4(HL)—Hess's law applications• ΔH⦵ = ΣΔHf⦵(products) − ΣΔHf⦵(reactants)• ΔH⦵ = ΣΔHc⦵(reactants) − ΣΔHc⦵(products)Syllabus objective1.2.5(HL)—Born-Haber cycle• Energy changes in ionic compound formation• Univalent and divalent ions• Interpret and determine cycle values; include lattice enthalpy and electron affinity termsSyllabus objective