Year 9 Science · Unit 2 · Lesson 12
Challenge Worksheet
Learning Goals
Design a mini-experiment
A scientist wants to test: "Can fractional distillation separate crude oil into fractions with measurably different flammability?" Plan the investigation below.
⚠ Safety note: This experiment involves flammable liquids. It must be conducted in a fume hood by a qualified chemist. Never attempt to ignite crude oil fractions without proper laboratory safety controls in place.
| What I will change (independent variable) | |
| What I will keep the same (controlled variables, list at least 3) | |
| What I will measure (dependent variable) | |
| My prediction, which fraction will be most flammable and why? | |
| How I would know if my prediction is wrong (falsification) | |
| One limitation of this experiment (besides safety) |
1. Bitumen (asphalt) and petrol both come from crude oil. Bitumen is used on roads; petrol runs car engines. Using what you know about chain length and boiling point, explain why these two fractions have such vastly different physical properties and uses despite coming from the same source material.
2. A scientist claims that fractional distillation could be used to separate any liquid mixture. Evaluate this claim: explain one situation where fractional distillation would work well, and one situation where it would fail. Justify both answers using the scientific principle behind the process.
Wrap Up
In one sentence, what was the main idea of this lesson?