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I am trying to understand the meaning of chemical energy. I saw in my book that chemical energy is stored in the bonds of chemical compounds and when the bonds are untied the chemical energy increases.

I don't understand, shouldn't the chemical energy decreases? I think this because the chemical energy is not stored anymore (because there are no bonds)

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This page describes the chemical energy level.

Edoardo
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    https://chemistry.stackexchange.com/questions/15250/how-do-breaking-chemical-bonds-turn-into-kinetic-energy – Mithoron Mar 25 '20 at 16:18
  • @EdV Thanks, I am wondering: could the chemical energy of two atoms considered as the energy that is needed to unhook two atoms? – Edoardo Mar 25 '20 at 16:32
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    This is binding energy of molecule. All this "chemical energy" is energy from reactions leading to compounds with lower enthalpy. – Mithoron Mar 25 '20 at 16:43
  • @Mithoron isn't the chemical energy the negative value of the binding energy of a molecule? It would make sense to me. Do you have other sources to suggest that help me understand better? thanks – Edoardo Mar 25 '20 at 16:52
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    Formally there's no such thing as "chemical energy". It's just a vague term for getting energy from reaction (or storing it). – Mithoron Mar 25 '20 at 16:56
  • @Mithoron Thanks, but why the chemical energy increases when there are no bonds? – Edoardo Mar 25 '20 at 17:01
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    https://chemistry.stackexchange.com/questions/63908/why-is-bond-breaking-endothermic https://chemistry.stackexchange.com/questions/13536/is-bond-formation-strictly-exothermic – Mithoron Mar 25 '20 at 17:15
  • @Mithoron thanks for your patience, so is chemical energy the potential of a chemical substance to undergo a chemical reaction to transform into other substances? right? – Edoardo Mar 25 '20 at 17:25
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    As @Mithoron said, there is no “chemical energy”. What matters are energy changes in chemical reactions. My PTFE beakers are chemically inert to most common reactions, but they would certainly react with molten Na, K, NaK, etc. Powdered and mixed with powdered Mg, they would serve as the oxidizing agent in the highly exothermic combustion of the Mg. What matters is the reactions potential reactants might engage in. – Ed V Mar 25 '20 at 17:27
  • It is always a bit semantic. Besides the comments above, you are correct as well. Energy can be seen as stored in a bound system if it breaks and rearrange into something at lower energy. Energy would be released. If one, instead, break a system, per se, energy is then stored in the fragments, as small as atoms, and become difficult to be pictorially described. This is to say that such sentences are very clear once one has already a clear picture. Otherwise, they can be confusing. The fact that you are asking means you are getting a clear picture. – Alchimista Mar 26 '20 at 07:51

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