2006-10-01 10:51:33 · 8 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
Its mostly various mixtures of hydrogen and carbon (H & C's ) but there are a number of other compounds in it to allow it to run in our engines today. These include engine knock inhibitors, various detergents, and various compounds that help in reducing emissions. These "special" compounds are, to us, in trace amounts so the majority of the mass is in hydrogen and carbon compounds.
Also, a note about the octane number:
The ratings for the fuel does not make them "better" than other fuels if you are running most modern engines. They just make them more expensive.
The octane rating of fuel is calculated by comparing its knocking characteristics with different mixtures of isooctane (C8H18) and n-heptane (C7H16). Isooctane had the highest knocking resistance when the rating system was invented so 100% isooctane has an octane rating of 100.
n-heptane has the lowest knocking resistance so 100% n-heptane has a rating of 0.
For example, a fuel rated 90 octane would have the same knocking characteristics that a mixture of 90% isooctane and 10% n-heptane would have.
In order to calculate this, a special engine called a CFR (Cooperative Fuels Research) engine. The petrol (or gasoline) is placed in the engine and run at various conditions. Then this is compared to how various mixtures of isooctane (C8H18) and n-heptane (C7H16) react in the engine.
So, what is the importance of the octane rating? First we need to know what knocking is.
Knocking is the ignition of the fuel before the spark plug fires. This is called auto-ignition. This occurs because, as we all know, as a gas is compressed its temperature rises. A low octane fuel-air mixture will ignite early as it is being compressed. This premature ignition means the mixture will already have combusted before the optimal timing for the engine, thus reducing engine efficiency and power generated.
Now, the amount of compression an engine does is basically what the compression ratio is. Generally, high performance engines such as those for sports cars have engines with high compression ratios. In order for them to operate at maximum efficiency, a high octane fuel is needed to allow the engine to compress the gas as designed.
However, most normal cars are designed for normal petrol (or gasoline). They also have advanced computer systems that monitor the engine characteristic to prevent knocking and there are all sorts of tricks automakers use also. This includes various spray geometries and analysis of flow inside the cylinders.
In the end, if your car manual does not specifically ask for super petrol (or premium gasoline) do not buy it! You will just be wasting your money. The engine will not perform any better since it will not be capable of producing higher compression ratios to take advantage of the higher octane gasoline. You'll just end up spending more at the pump!
2006-10-01 10:57:17 · answer #1 · answered by polloloco.rb67 4 · 1⤊ 0⤋
gasoline is mainly heptane and octane.... that is, compounds made of carbon and hydrogen, the alkanes... it is almost the same formula as methane and ethane (natural gas from the stove) or propane (gas for a backyard bar-b-q ) or butane (like a cigarette lighter)
The gasoline formula would be C8 H18 or something similar to that. .
2006-10-01 11:00:30 · answer #2 · answered by matt 7 · 1⤊ 0⤋
Carbon, Oxygen, and Hydrogen.
2006-10-01 10:58:45 · answer #3 · answered by dancingqueen378 2 · 1⤊ 1⤋
Carbon and hydrogen.
2006-10-01 10:54:34 · answer #4 · answered by zee_prime 6 · 2⤊ 0⤋
Gas and oline
2006-10-01 11:00:26 · answer #5 · answered by Jon W 5 · 1⤊ 0⤋
i think mainly carbon and hydrogen
2006-10-01 10:54:24 · answer #6 · answered by kahboom 2 · 2⤊ 0⤋
Go to:
http://en.wikipedia.org/wiki/Gasoline.
Hope this will help!!!
2006-10-01 20:31:00 · answer #7 · answered by Andreja K 3 · 1⤊ 0⤋
aromatics c8
2006-10-01 10:55:45 · answer #8 · answered by Anonymous · 0⤊ 1⤋