Molecular Formula of different Octane rating gasolines?

In summary, the molecular formula of gasoline is a complex mixture of hydrocarbons containing 5-12 carbon atoms per molecule. This formula has a direct impact on the octane rating of gasoline, with higher carbon numbers and branching increasing the rating and impurities such as sulfur decreasing it. Different octane ratings have different molecular formulas, with higher ratings having more complex and branched structures. The main difference in molecular formula between regular and premium gasoline is in the number and arrangement of carbon atoms, with premium gasoline having a higher proportion of larger, branched molecules. The molecular formula of gasoline can be altered through refining processes to improve its octane rating by removing impurities and adding certain additives.
  • #1
Quds Akbar
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TL;DR Summary
Cannot find enthalpy of combustion of different gasoline mixtures because I cannot find their molecular formulas, since they are mixtures and not compounds, is there a workaround?
Trying to calculate the enthalpy of combustion for gasolines with different octane ratings, 95 and 91 gasoline in particular. The thing is, they are mixtures and not compounds. To calculate the enthalpy of combustion, I am trying to find the molecular formula for each of the gasolines, in order to work out the grams per mole. Is there a way to find the molecular formula for gasolines, or a workaround to finding the enthalpy of combustion for these different gasoline mixtures?
 
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  • #2
If you know composition of the mixture, you can calculate its enthalpy of combustion as a weighted average.
 

What is the molecular formula of gasoline?

The molecular formula of gasoline is C8H18, which means that it contains 8 carbon atoms and 18 hydrogen atoms.

What is the difference between different octane rating gasolines?

The difference between different octane rating gasolines lies in the amount of octane present in the fuel. Higher octane rating gasolines have a higher percentage of octane, which makes them more resistant to pre-ignition and allows them to be used in high-performance engines without causing damage.

Why are there different octane ratings for gasoline?

Different octane ratings for gasoline exist to cater to different types of engines. Some engines, such as high-performance or turbocharged engines, require higher octane gasolines to function properly. On the other hand, lower octane gasolines are suitable for regular engines.

How is the octane rating of gasoline determined?

The octane rating of gasoline is determined through a process called the octane rating scale, which measures the fuel's ability to resist pre-ignition. This is done by comparing the fuel's performance to a mixture of n-heptane and iso-octane, which have octane ratings of 0 and 100, respectively.

What happens if I use the wrong octane gasoline for my car?

If you use a lower octane gasoline for an engine that requires a higher octane, it can cause knocking or pinging, which can damage the engine over time. On the other hand, using a higher octane gasoline in an engine that requires a lower octane will not provide any additional benefits and will be a waste of money.

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