Questions on Fossil fuels

1. The following table gives some RON values for some of the individual components that can be found in gasoline (petrol).

(a) Explain why the value for methylbenzene is greater than 100.

(b) Deduce the octane rating for a fuel that consists of 87% 2,2,4-trimethylpentane, 8% 2-methylheptane and 5% methylbenzene by volume.

2. Pure octane has a density of 0.703 g cm⁻³. A typical car gasoline tank holds 55 dm³ of fuel. If a driver uses one full tank of gasoline each week, calculate how much it contributes to his or her carbon footprint in tonnes per year. (Assume that that the driver carries no passengers and that gasoline has the same chemical and physical properties as pure octane).

3. During the process of cracking long chain hydrocarbons are broken down into smaller more usable compounds. State the equation for the cracking of decane, C₁₀H₂₂ to produce octane and state the main use for the other organic product formed.

4. Catalytic reforming of straight chain alkanes can be used to make branched alkanes in a process known as isomerization and to make aromatic compounds in a process known as aromatization.

(a) Deduce the equations for the isomerization of heptane to make 2,2-dimethylpentane and the aromatization of heptane to make methylbenzene.

(b) Explain why isomerization and aromatization are important processes.

Fossil fuels questions