2H2 + O2 ---> 2H2O
In the reaction, hydrogen and oxygen will be broken down into H and O, this is endothermic.
And forming 4 O-H bond is exothermic.
Overall, the exothermic process gives out more energy than the energy required by the endothermic process. So it is exothermic reaction.
My question is "why the energy required for exthermic process gives out more energy than the energy required by the endothermic process?", is it related to something strength of bbond, or others etc...? Similarly, the decomposition of NH3 into N2 and H2 is overall endothermic reaction, as the endothermic process required more energy than that the energy given out by the exothermic reaction, why?
更新1:
Please look deeply to my question.... It is not related to heat loss
