RUST

• ANODE hr?

  Fe -> Fe2+ +2e
• cathode hr?

  O2 + 2H2O + 4e = 4OH-
• product of cathode hr?

  4OH-
• reactants of cathode hr?

  O2 + 2H2O + 4e-
• OVERALL?

  2Fe(OH)3 = Fe2O3.H2O + 2H2O
• REACTANT OF VOERAL?

  2FE(OH)3
• SACRIFICAL ANODE?

  Piece of metal, connected to another metal thats more easily oxidised/corroded than the metal being protected from corrosion

  • oxidises preferentially to metal being protected
  • cant react with cold water
• how would coating iron prevent rust?

  stop water, oxygen and salt contacting iron

  • prevents cathode reaction
• coating stuff (overall point) prevents what reaction?

  cathode
• cathodic prevention?

  apply low voltage

  • power source provides a source of electrons in preference to iron