Year 9 Science · Unit 2 · Lesson 12
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Learning Goals
Read the graph
The bar chart below shows the approximate boiling point (or boiling point midpoint) for five key crude oil fractions. Study the graph, then answer the questions.
Data: Adapted from Australian Institute of Petroleum, Petroleum Refining in Australia (2019).
(a) Describe the trend shown in the graph. What happens to boiling point as you move from LPG to bitumen?
(b) Kerosene (jet fuel) has a boiling point range of about 150–250°C, while petrol has a range of about 40–200°C. Explain why jet fuel is collected at a lower height in the fractionating column than petrol.
(c) Why is fractional distillation classified as a physical separation method? Use evidence from the graph to support your answer.
Real-world scenario
Real-world context
Australia imports most of its crude oil for refining, as domestic reserves are limited. In 2021, the last large-scale oil refinery in Australia, Altona refinery in Victoria, operated by ExxonMobil, permanently closed. Today, Australia imports all of its refined fuels (petrol, diesel, jet fuel) directly from overseas refineries in Singapore, South Korea, and Japan. The federal government has identified this as a critical fuel security risk, particularly for aviation and defence.
(a) Classify crude oil as a mixture, compound, or element. Justify your answer using what you know about its composition.
(b) Explain why losing Australia's refinery capacity is more serious than simply losing access to crude oil supply. Use your knowledge of fractional distillation in your answer.
1. A student says "longer hydrocarbon chains are collected higher up in the distillation column." Is this correct? Explain your answer.
2. Diesel is used for trucks and ships, while LPG is used for cooking. Using boiling point and chain length data, explain why these two fractions have such different practical uses.
Wrap Up
In one sentence, what was the main idea of this lesson?