What is the enthalpy change of a reaction Delta H in terms of bond enthalpies of reactants and products? (Hard)
Answer and explanation
Correct answer: D. Delta H = Sum(Bond enthalpy of reactants) - Sum(Bond enthalpy of products)
- Step 1: Breaking chemical bonds in reactants absorbs energy (endothermic, positive bond enthalpy). Step 2. Forming new bonds in products releases energy (exothermic, negative). Net Delta H = Sum(Bonds broken) - Sum(Bonds formed). Answer: Delta H = Sum(Bond enthalpy of reactants) - Sum(Bond enthalpy of products). Why not the others: Products - Reactants is for enthalpy of formation, not bond energies; addition is invalid; division is non-physical.
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