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I don't know what are the molecular reasons that two substance will form another substance.

Why oxygen molecules can form to ozone molecules? Why hydrogen and oxygen makes water? What are the physical foundations for it? Is it possible to explain it with quantum mechanics?

EDIT: There are models for chemical reactions in terms of continuum mechanics (it is called "Mixture Theory"). But I don't understand Mixture Theory!

I know basics of continuum mechanics, but NO continuum mechanics of mixtures which can react with each other. Can someone explain this pdf:

http://www.mech-wilmanski.de/mixturesrome.pdf

kryomaxim
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Basically, forming chemical bonds releases energy. E.g. two atoms join together to make a chemical bond between them and release energy. Thereby, atoms/ molecules join together to get the stability (lesser the energy, higher the stability). You can do a simple calculation, calculate the total energy stored in one mole of Oxygen molecules (bond energy between O-O, per mole), two moles of hydrogen molecules (bond energy between H-H, per two moles), Then find out the energy stored in two moles of water molecules (bond energy between H-O, per two moles). You will see that the reaction of forming water is exothermic.

As a summary

at standard conditions, this reaction releases 285.8 kJ of energy.

H2(g) + 1/2 O2 -> H2O (l), enthalpy = -285.8 kJ per mol

negative value tells that the heat is released

This is why mixing HCl and NaOH releases heat. So overall, the physical foundation is gaining stability!

Kosala
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