1. Q1) What conditions are present that enable rusting?
Q2) How do you think rusting of the Eiffel Tower is prevented?
Q3) Why is it important to prevent the Eiffel Tower from rusting?
Q4) How could the design of the Eiffel Tower have been improved in order to prevent rusting?

2. Q3) Tourist attraction – makes 22 million euros a year.
Q1) Water and Oxygen
Q2) It is painted once every 7 years – this takes 18 months to complete and costs 4million euros!
Q3) Tourist attraction – makes 22 million euros a year.
Q4) Any reasonable answer
Q4 sparked a good debate. Suggestions included: wood (fire risk), Al (not discovered), Au (too expensive), plastic (unsightly, unstable).

3. Rusting

4. What you need to know about rusting
Rusting is the corrosion of iron (& steel). Other metals can CORRODE but not rust
It is an oxidation process (addition of oxygen)
Rust is hydrated iron oxide
Both water and oxygen (from the air) are required for rusting
Salt and other electrolytes (e.g. acid) can speed up rusting

5. Group practical:
Design an experiment to prove that oxygen and water are needed for rusting to occur and whether salt increases the rate of rusting
Work in groups of 2
You will be given the following
Nails
Stoppers
Paint
Salt – at least 4 types
Access to water
Anhydrous calcium chloride

6. Write answers in the back of your book
What is the question?
Write answers in the back of your book
Only iron
2) Water AND oxygen
3) Anhydrous calcium chloride
4) Salts and other electrolytes
5) Hydrated iron oxide

7. How can we prevent this from happening?

8. Rust prevention

9. There are 2 main methods to help prevent rusting
1) Putting a barrier between the metal and the air and moisture e.g. grease, paint, plastic, unreactive metal
2) Sacrificial protection-The iron is covered or connected to a more reactive metal so it will ‘corrode’ ahead of the iron e.g. Magnesium or Zinc

10. Decide whether these chemicals will react together when heated
Magnesium + copper(ll) oxide
Iron + magnesium oxide
Zinc + magnesium oxide
Copper + zinc oxide
Calcium + zinc oxide
For those that react:
Write a word equation
Write a balanced equation

11. Answers
Magnesium + copper(ll) oxide → Copper + magnesium oxide Mg + CuO → Cu + MgO Iron + magnesium oxide – No Reaction Zinc + magnesium oxide – No Reaction Copper + zinc oxide – No Reaction Calcium + zinc oxide → Zinc and Calcium oxide Ca + ZnO → Zn + CaO

12. Displacement reactions of solutions
A more reactive metal will displace a less reactive metal from a solution of one of its salts. For example:
magnesium + copper(II) sulfate → copper + magnesium sulfate
Mg(s) + CuSO4(aq) → Cu(s) + MgSO4(aq)
In this reaction, the blue colour of the copper(II) sulfate fades as it is used up (magnesium sulfate solution is colourless). We would also see copper metal forming.

13. Decide whether these will react:
Iron + copper(ll) sulphate solution
Silver + calcium nitrate solution
Zinc + copper (ll) sulphate solution
For those that react:
Write a word equation
Write a balanced equation (extension)

14. Answers
Iron + copper(ll) sulphate solution – No Reaction
Silver + calcium nitrate solution – No Reaction
Zinc + copper (ll) sulphate solution → Copper and zinc sulphate solution
Zn(s) + CuSO4(aq) → Cu(s) + ZnSO4(aq)