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CHEMISTRY LEVEL 3C
(CHM 315109)
CORROSION
THEORY SUMMARY & REVISION QUESTIONS
(CRITERION 5)
Tasmanian TCE Chemistry Revision Guides by Jak Denny are licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
INDEX:
PAGES • INTRODUCTION • EFFECTS OF CORROSION • ELECTROCHEMICAL EFFECTS • FACTORS AFFECTING CORROSION • THE RUSTING OF IRON • IDENTIFYING ANODES & CATHODES • DIAGRAMMATIC SUMMARY • DIFFERENTIAL AERATION • DIFFERENT METALS IN CONTACT • CORROSION PROTECTION • THE CORROSION OF ALUMINIUM • THEORY SUMMARY • REVISION TEST • REVISION TEST ANSWERS
2
3 4 5 6 7 7 8 9-10 11-12 13-16 17 18 19-20 21
© JAK
CHEMISTRY LEVEL 3C (CHM 315109) CORROSION (CRITERION 5)
INTRODUCTION:
Corrosion is a general term referring to the DESTRUCTIVE OXIDATION OF METALS caused by oxidising agents in the surrounding chemical environment. The most commonly encountered form of corrosion is rusting which is the term specifically applied to the destructive oxidation of iron and steel. (The term rust is only to be used with respect to iron and steel). Practically all metals will undergo corrosion and even the noble metals like platinum and gold will corrode if they are in contact with very powerful oxidising agents. In many cases, the corrosion of a metal results in the formation of the metal oxide or hydroxide. However in some cases, other corrosion products such as carbonates, sulfides and even nitrides may be formed. e.g.
METAL
IRON (Fe) ZINC (Zn) ALUMINIUM (Al) MAGNESIUM (Mg) SILVER (Ag)
POSSIBLE CORROSION PRODUCTS
Fe2O3 Fe(OH)3 Fe2O3.H2O ZnO Zn(OH)2 ZnCO3 Al2O3 Al(OH)3 MgO Mg(OH)2 Mg3N2 Ag2O Ag2S
* In this study unit on corrosion, we shall be principally concerned with the corrosion of IRON with rust being represented as Fe(OH)3 although Fe2O3.H2O is a preferred chemical formula for rust.
Corrosion damage to cars costs Australians millions of dollars each year! 3 © JAK
THE EFFECTS OF CORROSION:
The effects of
(CHM 315109)
CORROSION
THEORY SUMMARY & REVISION QUESTIONS
(CRITERION 5)
Tasmanian TCE Chemistry Revision Guides by Jak Denny are licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
INDEX:
PAGES • INTRODUCTION • EFFECTS OF CORROSION • ELECTROCHEMICAL EFFECTS • FACTORS AFFECTING CORROSION • THE RUSTING OF IRON • IDENTIFYING ANODES & CATHODES • DIAGRAMMATIC SUMMARY • DIFFERENTIAL AERATION • DIFFERENT METALS IN CONTACT • CORROSION PROTECTION • THE CORROSION OF ALUMINIUM • THEORY SUMMARY • REVISION TEST • REVISION TEST ANSWERS
2
3 4 5 6 7 7 8 9-10 11-12 13-16 17 18 19-20 21
© JAK
CHEMISTRY LEVEL 3C (CHM 315109) CORROSION (CRITERION 5)
INTRODUCTION:
Corrosion is a general term referring to the DESTRUCTIVE OXIDATION OF METALS caused by oxidising agents in the surrounding chemical environment. The most commonly encountered form of corrosion is rusting which is the term specifically applied to the destructive oxidation of iron and steel. (The term rust is only to be used with respect to iron and steel). Practically all metals will undergo corrosion and even the noble metals like platinum and gold will corrode if they are in contact with very powerful oxidising agents. In many cases, the corrosion of a metal results in the formation of the metal oxide or hydroxide. However in some cases, other corrosion products such as carbonates, sulfides and even nitrides may be formed. e.g.
METAL
IRON (Fe) ZINC (Zn) ALUMINIUM (Al) MAGNESIUM (Mg) SILVER (Ag)
POSSIBLE CORROSION PRODUCTS
Fe2O3 Fe(OH)3 Fe2O3.H2O ZnO Zn(OH)2 ZnCO3 Al2O3 Al(OH)3 MgO Mg(OH)2 Mg3N2 Ag2O Ag2S
* In this study unit on corrosion, we shall be principally concerned with the corrosion of IRON with rust being represented as Fe(OH)3 although Fe2O3.H2O is a preferred chemical formula for rust.
Corrosion damage to cars costs Australians millions of dollars each year! 3 © JAK
THE EFFECTS OF CORROSION:
The effects of