When fire is created. In which like methane and oxygen molecules in a burner they move around and when he give them a spark they gain energy and move faster and break apart. And hit each other and loose energy in friction and sound, but what is this saying that they create more energy than the energy required to start the reaction. I really don’t understand that
In: Chemistry
First it’s important to realise that energy can’t be *created* or *destroyed*. It can only be transferred into various forms, and one of those forms is being in chemical bonds.
Breaking bonds requires you to input energy, to pull two things apart. Forming those bonds means the involved atoms/molecules reach a lower energy state, and that energy has to be released in some form. The amount of energy required/released depends on how strong the bonds are (and therefore how stable the molecule is).
So for burning methane, the chemical reaction is
CH4 + 2O2 –> CO2 + 2 H2O.
The energy required to break the C-H bonds in the methane and the O=O bonds in the oxygen, is less than the energy released when the C=O and O-H bonds form in the products. So it releases more energy than it took to react.
The spark provides the thermal energy to those first few methane and oxygen molecules to react and break the chemical bonds. That reaction releases heat, which causes more molecules to react, releasing more energy, and so on.
This is why you can’t really burn water. Those O-H bonds are pretty strong, and whatever you’re burning the water with would have to have even stronger bonds to form during burning for the reaction to progress.
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