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I was software engenneering student at college, i'm so out from the chemistry domain, but in high school we studied physics and chemistry, and now i have more than 6 years i didn't study about chimestry nor physics, so i have two questions.

1) I wondred from a thing, for ex: in cars, usualy we mesure the power in hp, which is equivalent to 745,7 watt, imagining a car engine which produces 100hp so it produces around 74570 watt, this is huge power, alghout we many lose many of power produced by the gasoline as a heat, so how much hydrocarbons free power??!!

2) How does the gasoline store all this power?!!! in other words, what does happens exactly to gasoline when burning/exploding to give this huge power??

these just a general questions, in this life i really like to understand how things work, even if they're so out for me and don't mean anything, but it still funny to understand how things works, and if i'm understanding something falsy or anything, just let me know it :)

La VloZ Merrill
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  • related http://chemistry.stackexchange.com/questions/3947/what-is-the-nature-of-chemical-energy – Mithoron Apr 08 '16 at 00:58
  • Welcome to Chemistry.SE! Take the [tour] to get familiar with this site. Mathematical expressions and equations can be formatted using $\LaTeX$ syntax. It appears to me you are in general asking about the combustion of hydrocarbons, i.e. fuel. This is a bit too broad for this site. Please try to narrow down the scope of your question to a specific problem you have with the process. You might want to start reading some Wikipedia article. – Martin - マーチン Apr 08 '16 at 05:41

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In chemical reactions, bonds are formed, and these involve significant amounts of energy. For example, when you burn octane in oxygen, $\ce{2C_8H_18 + 25O2 → 16CO_2 + 18H_2O}$, it releases 48 kJ per gram of octane. Energy changes accompany chemical reactions because bonds are being broken and new ones are formed. It is energy releasing to form a bond, and the stronger a bond is, the more energy is released. For hydrocarbons, the carbon to hydrogen bonds are quite weak, so when they form much stronger bonds, as in carbon dioxide and water, a lot of energy comes out.

Sometimes if you take a chemical reaction, it absorbs heat because the old bonds were stronger.

Yunfei Ma
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