Question

octane number

Answer 1

so i understand when an aliphatic molecule undergoes alkylation, it becomes branched molecule, so better burning in cars motors.

so i know that the more branches better the burn of gasoline, so what does that hve to do with octane number? is the branches the octane number?
if not what is it? what determines it?

Answer 2

@matt101 i was wondering if you might know maybe? its fine if you dont

Answer 3

do you happen to lknow this too? @phuong.tong

Answer 4

I took organic chemistry long time ago, I just remember that the higher octane will allow for higher compression ratio which relate to energy released. Let me think think a little bit more how to explain better

Answer 5

When octane is burned , it is undergo combustion process which creates CO2 and H20 that relate to copression ratio that I mention above.

Answer 6

The octane number is a measure of how much compression a type of fuel can withstand before igniting. The reason this is important is that the higher the octane number, the more controlled the burning will be, and the less likely it will be to just explode.

The octane number isn't a count of the branches in your hydrocarbon, is not reflective of the amount of energy in your fuel, and doesn't have to mean your fuel is octane (or even derived from it), although fuel often does contain octane. The reason it's called "octane number" is because the fuel of interest is being compared to a reference fuel that is primarily composed of an octane isomer.