CORROSION Corrosion is a reaction which takes place on the surface of a metal
During corrosion: <ul><li>The metal element changes into a compound </li></ul><ul><li>Magnesium metal + oxygen in air  </l...
WHAT IS RUSTING? <ul><li>The corrosion of iron is called rusting </li></ul><ul><li>For iron to rust you need </li></ul><ul...
The battle against corrosion <ul><li>Materials </li></ul><ul><li>Beaker </li></ul><ul><li>W tube </li></ul><ul><li>3 nails...
<ul><li>Ferroxyl indicator  is a pale yellow-coloured solution which turns blue when Fe 2+  ions are produced. </li></ul><...
<ul><li>Procedure </li></ul><ul><li>We take three iron nails: </li></ul><ul><li>1)Nail with Mg ribbon attached to it </li>...
What is about to happen?
<ul><li>1)No  B lue , no corrosion of iron </li></ul><ul><li>Mg loses e -  more readily than iron. </li></ul><ul><li>Mg  M...
QUESTION 1 <ul><li>Attaching a metal that is higher in the ECS Magnesium (Mg) </li></ul><ul><li>A) Protects iron from corr...
<ul><li>Attaching a metal that is lower in the ECS Copper (Cu) </li></ul><ul><li>A) Protects iron from corrosion </li></ul...
<ul><li>Attaching  a metal that is higher in the ECS (Mg)protects iron from corrosion, but attaching one that is lower dow...
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Corrosion

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Corrosion

  1. 1. CORROSION Corrosion is a reaction which takes place on the surface of a metal
  2. 2. During corrosion: <ul><li>The metal element changes into a compound </li></ul><ul><li>Magnesium metal + oxygen in air </li></ul><ul><li>2Mg + O 2 </li></ul><ul><li>The metal atoms loose electrons to form metal ions </li></ul><ul><li>Mg </li></ul><ul><li>This loss of electrons is called OXIDATION </li></ul>Magnesium oxide 2MgO Mg 2+ + 2e -
  3. 3. WHAT IS RUSTING? <ul><li>The corrosion of iron is called rusting </li></ul><ul><li>For iron to rust you need </li></ul><ul><li>Water (H 2 O) </li></ul><ul><li>Oxygen from air (O 2 ) </li></ul><ul><li>2Fe (s) +2H 2 O (l) + O 2 (g) 2Fe 2+ (aq) + 4OH - (aq) </li></ul>
  4. 4. The battle against corrosion <ul><li>Materials </li></ul><ul><li>Beaker </li></ul><ul><li>W tube </li></ul><ul><li>3 nails </li></ul><ul><li>Magnesium ribbon </li></ul><ul><li>Copper ribbon </li></ul><ul><li>Ferroxyl indicator </li></ul><ul><li>Sodium chloride </li></ul>
  5. 5. <ul><li>Ferroxyl indicator is a pale yellow-coloured solution which turns blue when Fe 2+ ions are produced. </li></ul><ul><li>Sodium chloride (common salt) is an electrolyte, rusting occurs faster when an electrolyte is present. </li></ul>
  6. 6. <ul><li>Procedure </li></ul><ul><li>We take three iron nails: </li></ul><ul><li>1)Nail with Mg ribbon attached to it </li></ul><ul><li>2)Bare Nail </li></ul><ul><li>3)Nail with Cu ribbon attached to it </li></ul><ul><li>We place the nails in the Sodium chloride solution and we add some drops of ferroxyl indicator solution </li></ul>
  7. 7. What is about to happen?
  8. 8. <ul><li>1)No B lue , no corrosion of iron </li></ul><ul><li>Mg loses e - more readily than iron. </li></ul><ul><li>Mg Mg 2+ + 2e - </li></ul><ul><li>2)Some Blue , corrosion of iron </li></ul><ul><li>Fe Fe 2+ + 2e - </li></ul><ul><li>3)More intense Blue , corrosion of iron. </li></ul><ul><li>Fe loses e - more readily than copper. </li></ul><ul><li>Fe Fe 2+ + 2e - </li></ul>
  9. 9. QUESTION 1 <ul><li>Attaching a metal that is higher in the ECS Magnesium (Mg) </li></ul><ul><li>A) Protects iron from corrosion </li></ul><ul><li>B) Speeds up corrosion </li></ul>
  10. 10. <ul><li>Attaching a metal that is lower in the ECS Copper (Cu) </li></ul><ul><li>A) Protects iron from corrosion </li></ul><ul><li>B) Speeds up corrosion </li></ul>QUESTION 2
  11. 11. <ul><li>Attaching a metal that is higher in the ECS (Mg)protects iron from corrosion, but attaching one that is lower down (Cu) speeds up its corrosion. </li></ul>

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