Year 9 Science · Unit 2 · Lesson 03
Foundation Worksheet
Learning Goals
True or false? Fix the false ones
Circle T or F. If a statement is false, correct it on the line.
Rusting is a physical change because the iron only changes shape.
Correct it:
Gold is used in jewellery partly because it reacts very little with air and water.
Correct it:
Aluminium corrodes more slowly than iron because its oxide layer is protective.
Correct it:
Flammability is a physical property because nothing changes permanently when something burns.
Correct it:
1. Name two chemical properties of iron and describe what happens to the iron in each one.
Sort it: physical or chemical change?
Write each change in the correct box. Ask yourself: is a new substance made?
Physical change
Chemical change
Investigation: what makes iron rust?
A class left five iron nails in each of four test tubes for two weeks, weighing each set before and after. Rust weighs more than the iron it forms from, because oxygen and water join onto the iron.
| Tube | Conditions | Mass before (g) | Mass after (g) | Rust seen |
|---|---|---|---|---|
| A | Dry air only | 10.00 | 10.00 | None |
| B | Boiled water under oil (no air) | 10.00 | 10.01 | Almost none |
| C | Air and water | 10.00 | 10.12 | Some |
| D | Air and salt water | 10.00 | 10.31 | A lot |
Source: sample class results.
2. Calculate the mass gained by the nails in tube D.
Answer g
3. Compare tubes A, B and C. Which two substances must iron have in order to rust? Use the results as evidence. Then say what tube D suggests about steel structures built near the ocean.
4. The Sydney Harbour Bridge is continuously repainted to prevent corrosion. Using your knowledge of iron’s chemical properties, explain why the paint is necessary and predict what would happen if the repainting stopped.