AP Chemistry · Unit 6: Thermochemistry
6.7 Bond Enthalpies
In short
You are expected to understand that chemical reactions involve breaking bonds (which requires an input of energy) and forming bonds (which releases energy), thereby changing the potential energy of the system.
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What else do you need to know about Bond Enthalpies?
You must be able to estimate the overall enthalpy change of a reaction by summing the average bond energies of all bonds broken in the reactants and comparing it to the sum of the average bond energies of all bonds formed in the products. The depth requires concluding whether a reaction is endothermic or exothermic based on which of these two energy quantities is greater.
How is Bond Enthalpies tested on the exam?
On the AP Exam, you must be able to translate between a balanced chemical equation and a calculation involving the energies of bonds broken and formed. A common pitfall examiners note is that many students struggle to correctly determine the number and types of bonds that were broken and made in the reaction. You must be able to accurately identify these bonds (often requiring them to draw or visualize Lewis structures) and apply mathematical routines to calculate or estimate the overall enthalpy of the reaction.
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Bond Enthalpies: common questions
What do you need to know about Bond Enthalpies for AP Chemistry?
You are expected to understand that chemical reactions involve breaking bonds (which requires an input of energy) and forming bonds (which releases energy), thereby changing the potential energy of the system.
How is Bond Enthalpies tested on the AP Chemistry exam?
On the AP Exam, you must be able to translate between a balanced chemical equation and a calculation involving the energies of bonds broken and formed. A common pitfall examiners note is that many students struggle to correctly determine the number and types of bonds that were broken and made in the reaction.
Where does Bond Enthalpies fit in AP Chemistry?
Bond Enthalpies is topic 6.7 in Unit 6: Thermochemistry of AP Chemistry.
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