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Gh0strid3r
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#1
How to calculate heat transfer using bond energies
(IGCSE)/ olevels
(IGCSE)/ olevels
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username2752874
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Enthalpy Change (or heat transfer) = Energy of the bonds broken - Energy of the bonds formed
Remember, bond breaking is positive while bond forming is negative
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Sonia2598
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Gh0strid3r
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#5
(Original post by Sonia2598)
Is there a question for it?
Is there a question for it?
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Sonia2598
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So you do sum of energy required to break bonds which is the reactants minus sum of energy required to form bonds which is the products
So 678-862= -184KJ
So 678-862= -184KJ
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gingembread
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Overall energy change = (energy required to break bonds) - (energy released by forming bonds).
So, if you calculate the energy needed to break the H-H and the Cl-Cl bond using the data in the table, and subtract the energy released by forming two H-Cl bonds, you'll get the overall energy change.
Exothermic reactions are when energy is released to the surroundings, so the energy released by breaking bonds is greater than the energy used to break them. You can prove this by getting an overall energy change that's negative from this calculation. (:
So, if you calculate the energy needed to break the H-H and the Cl-Cl bond using the data in the table, and subtract the energy released by forming two H-Cl bonds, you'll get the overall energy change.
Exothermic reactions are when energy is released to the surroundings, so the energy released by breaking bonds is greater than the energy used to break them. You can prove this by getting an overall energy change that's negative from this calculation. (:
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