IMG_0001_NEW_0036 - + AlrO, oxide layer protects intemal...

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Corrosion Corrosion = oxidation of a metal Electrochemical process O2+2H2O + 4e- -+ 4OH- zP: +0.40 v Easity corroded metals: E"(metal) < F(Oz) p"--ypg2+*2e- -E :<4-44V) +02-+Fe2O3 Al -+Al3*+3e- - E :-(-1.66V) +02-+Al2O3 + E""o(metal oxidation): +ve -+ spontaneous Corrosion resistant metals: E (metal) > F(Ot) 6u --e' 4s3+ * 3e -E : -{+1.50 V) Corrosion enhanced significantly by acid Oz + H* + 4{ -+ zHzO,E : +1.229 V Formation of Oxide Layer -* helps resist corrosion Al
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Unformatted text preview: + AlrO, oxide layer protects intemal atoms-+ Anodizing of aluminum Gorrosion of lron Rusting : Electrochemical process (not direct oxidation) Nonuniformity in metal -> Anodic regions - Fe more easily oxidized: Fe -+ Fe2* + 2t Electrons flow through metal (: wire) Fe2* travel through surface moisture (: salt bridge) __i LJ Cathodic regions: 02 + 2H2O + 4{ -+ 4OH-To form rust: RUST 4Fe2* + 02 + @+2n)2IJ^2O + Fe2O3 'nH2O + 8ff fming a pir...
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This note was uploaded on 12/27/2011 for the course CHEM 122 taught by Professor Williams during the Fall '10 term at Simon Fraser.

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