Year 8 Science · Unit 3 · Lesson 4
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Learning Goals
Compare two
Complete the table to compare exothermic and endothermic reactions across each feature.
| Feature | Exothermic reaction | Endothermic reaction |
|---|---|---|
| What happens to temperature of surroundings? | ||
| Energy direction | ||
| Does it feel hot or cold to touch? | ||
| One everyday Australian example | ||
| Is it a chemical change? (Yes/No) |
Order the steps
Number the steps from 1 to 6 to show how a scientist would investigate whether a chemical reaction has occurred when mixing two unknown liquids. Step 1 happens first.
| Order (1–6) | Step |
|---|---|
| Collect multiple observations: colour, temperature, any gas bubbles, any solid forming, any light or sound. | |
| Mix the two liquids in a clear container and begin observing immediately. | |
| Record starting conditions: colour, temperature, and appearance of each liquid before mixing. | |
| Count how many pieces of evidence were observed and consider whether each could have a physical explanation. | |
| Write a conclusion: if two or more clues point to new substances forming, classify as a chemical reaction. | |
| Plan the investigation: prepare equipment, identify a safe environment, and note what evidence you will look for. |
1. A student burns a candle on a balance and records the mass dropping over time. They conclude: "Mass is not conserved in chemical reactions." Explain why this conclusion is incorrect and what is actually happening to the mass.
2. ANSTO scientists producing medical isotopes monitor multiple clues simultaneously. Name two pieces of evidence they might measure during a chemical reaction and explain what each one tells them about the reaction's progress.
Wrap Up
In one sentence, what was the main idea of this lesson?