What keeps gasoline burning?

Question

Let's say you have gasoline. I know it is a complex set of chemicals so for simplicity sake, let's say its just C8H18 (octane). If you provide an initial heat source to light it, it still continues to burn after that heat source has been removed. So what is keeping it burning?

My guess would be that the chemical equation for C8H18 combining with O2 has an output of extra energy (possibly in the form of electrons ionized out of the atoms) that hits other C8H18 atoms and provides them with extra energy, thus raising their temperature and making them able to combine with O2 ad infinitum (or until you run out of gasoline). In essence:

2 C8H18 + 25 O2 --> 16 CO2 + 18 H2O + Energy

Is my thought process correct or am I missing something?

Robert D · Accepted Answer

You are basically correct.  Flammable organic liquids have an autoignition temperature.  If the temperature of the liquid is above that temperature the gasoline will continue to burn or if you extinguish the flame momentarily the flame will reignite above the autoignition temperature.  Of course, the presence of O2 is also required.  The combustion reaction you have shown is an exothermic reaction and will help sustain the burning of the gasoline.

Hope this is helpful to you.  JIL HIR

What keeps gasoline burning?

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