1.1. A team of aerospace engineers is evaluating a prototype liquid fuel, heptane (C₇​H_16​), for use in a portable heating device.

The engineers test the fuel inside a sealed titanium chamber to measure its energy output.

The heptane used in the prototype is sourced from the petrol fraction of crude oil.

Describe the industrial process used to separate the petrol fraction from crude oil.

1.2. The pure heptane prototype fuel is classified as a saturated hydrocarbon.

Which statement explains what is meant by saturated?

1.3. The unrefined heptane fuel contains trace amounts of sulfur. When the fuel is burned, the sulfur reacts with oxygen to form sulfur dioxide.

i) Write the balanced chemical equation for this reaction.

[1]

ii) Explain the environmental impact of venting sulfur dioxide gas into the atmosphere.

[3]

1.4. The engineers compared heptane, C_7​H₁₆, with dodecane, C₁₂H₂₆.

Figure 11 shows some of their properties. The flash point is the lowest temperature at which a liquid produces enough vapour to ignite.

Figure 11

Use the data in Figure 1 and your knowledge of intermolecular forces to explain why dodecane is harder to ignite than heptane.

1.5. To create a fuel blend that ignites more easily, the engineers crack some of the heptane molecules.

Write the balanced equation to show the cracking of one molecule of heptane, C₇​H_16​, to produce one molecule of propene, C₃​H_6​, and one other molecule.

1.6. The engineers test the newly cracked fuel mixture with bromine water to confirm that alkenes are present.

What type of chemical reaction occurs when an alkene reacts with bromine?