Enthalpy change of combustion is exothermic becauase:
Correct answer: B. Energy released in bond making is greater
- A. Energy released in bond breaking is greater
- B. Energy released in bond making is greater
- C. Energy absorbed in bond breaking is greater
- D. Energy absorbed In bond making is greater
Explanation
Breaking these bonds requires energy to be absorbed by the reaction. But then, new bonds form between hydrogen and oxygen and between carbon and oxygen. For this reaction, the energy released is larger than the energy absorbed. This means combustion has an overall negative enthalpy and is an exothermic reaction.
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About Exothermic and Endothermic Reactions
Exothermic reactions release heat to the surroundings and have negative enthalpy change, while endothermic reactions absorb heat and have positive enthalpy change. The topic uses energy profiles to identify reactants, products and activation energy, and includes bond energy, enthalpy diagrams, calorimetry and Hess's law for calculating overall heat changes.
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