1. Corrosion

2. Success… In order to be successful in this lesson you must be able to:
Learning Objectives:
In order to be successful in this lesson you must be able to:
Explain the difference between rusting and corrosion and explain how to prevent rusting
Success…

3. iron + water + oxygen  rust
Corrosion
Many things are made of iron. However, iron has one major drawback – it goes rusty.
iron water oxygen  rust
Rust is the product of the corrosion of iron.
Other examples include silver tarnish and the green film that forms on copper or brass objects.

4. Ways to stop corrosion
There are many ways to stop corrosion from occurring:
PAINTING: so metal is not exposed to air.
COATING WITH OIL, GREASE or TAR: for metal surfaces which can not be painted.
COATING WITH PLASTIC: so metal is not exposed.
COATING WITH METAL: eg. Galvanising Coating iron with a layer of zinc slows corrosion because the zinc is more reactive than iron.

5. Rusting can be useful! RUSTING CAN BE USEFUL!
Hand warmers worn by skiers are made of a powder of iron, salt and sawdust. When shaken vigorously, iron rusts, producing heat.

6. Watch your teacher demonstrate the different conditions of rusting
What causes rusting?
Watch your teacher demonstrate the different conditions of rusting

7. What causes rusting? QUESTIONS:
Write an aim and list the materials required for the experiment.
AIM: To investigate what causes rusting.
MATERIALS:
4 x test tubes
10 ml measuring cylinder
Test tube rack
Silica gel / calcium chloride
5 x iron nails
Spatula
Distilled water
Rubber stopper
Oil

8. What causes rusting? QUESTIONS: Record the results obtained Test tube
Conditions
Observations 1
Air & Water
Iron wool rusts. Some falls to bottom of test tube. 2
Water & Oil
Small amounts of rust 3
Air & Solid Calcium Chloride
No rust 4
Oil

9. What causes rusting? QUESTIONS:
In which test tubes did the iron wool rust quickly? Why?
Test tubes 1 & 5 because they have iron, air & water together.
In which test tubes did the iron wool not rust? Why?
Test tubes 2, 3 & 4 because they either air or water was missing.

10. What causes rusting? CONCLUSIONS:
What conditions are necessary for the iron wool to rust?
Iron needs air and water together for rusting. Salt speeds up the rusting process.
How could you stop the iron from going rusty?
You would exclude water or air or both. This can be done by covering the metal with paint, oil, plastic or another metal. You could also keep the air dry by using silica gel (calcium chloride).

11. What causes rusting? ACTIVITY: What is meant by the following terms:
CORROSION: Reaction of metals with oxygen and water in which they dissolve away.
RUSTING: The corrosion of iron.
GALVANISED: Iron covered with zinc.
What are the three reactants needed for corrosion?
Iron, water & air.

12. What causes rusting? ACTIVITY:
Some clothes stands are coated with a white plastic. When this plastic ages and cracks there is rust. Why is this?
Cracks in the plastic allow air and water to react with the iron inside.

13. Rusting
Using Collins book 3 pages 78 – 79 & 80 – 81 produce a poster on rusting
Success Criteria:
What is rust?
Explain why gold jewellery always stays shiny and beautiful
What is stainless steel and why is it important?
Ways in which rusting of iron can be prevented
What is galvanising?
Why aluminium does not corrode?