If Fe is left outside it will eventually rust.What causes this redox reaction?Fe changes into Fe2+ and O2 changes into OH1-.Write 2 balanced half reactions to show these oxidation reduction reactions.
Fe Fe2+ + 2e1-
O2 OH1- + H2O3H1+ +4e1- +2 2 4
2Fe + 3H1+ + O2 2Fe2+ + OH1- + H2O+3OH1- +3OH1-
2Fe + 3H2O + O2 2Fe2+ + 4OH1- + H2O- H2O - H2O
2Fe + 2H2O + O2 2Fe2+ + 4OH1-
Fe
H2O
2Fe
O2
2Fe + 2H2O + O2 2Fe2+ + 4OH1-
2Fe2+
O2 + 2H2O + 4e1- 4OH1-
2Fe 2Fe2+ + 4e1-
4e1-4OH1-
2Fe
O2
2Fe + 2H2O + O2 2Fe2+ + 4OH1-
2Fe2+
O2 + 2H2O + 4e1- 4OH1-
2Fe 2Fe2+ + 4e1-
4e1-4OH1-
Over time the Fe(OH)2 accumulates as a solid due to low solubility and is further oxidized by H2O and O2 into Fe(OH)3
2Fe
O22Fe2+
4e1-4OH1-
Over time the Fe(OH)2 accumulates as a solid due to low solubility and is further oxidized by H2O and O2 into Fe(OH)3
Write a balanced equation showing the formation of ferric hydroxide from ferrous hydroxide, water and oxygen.
2Fe
O22Fe2+
4e1-4OH1-
Write a balanced equation showing the formation of ferric hydroxide from ferrous hydroxide, water and oxygen using the oxidation number method.
Fe(OH)2 + O2 + H2O Fe(OH)3
2+ 3+0 2-
1e1-/Fe1e1-/Fe(OH)2
2e1-/O4e1-/O2
4 4
Balance O usingwater
2
If Fe objects are buried under ground where there is water with dissolved oxygen in it how can they be protected from rusting?Hint: look at the Standard Reduction Table and find the reduction of iron.If another metal with a weaker pull on electrons is placed in contact with the iron it will be oxidized instead of the iron.Iron will be reduced when combined with a metal which is a weaker oxidizing agent.
underground Fe tank
Mg
Fe2+ + 2e1- Fe - 0.45 VMg2+ + 2e1- Mg - 2.37 VMg Mg2+ + 2e1- - 2.37 VFe2+ + Mg Mg2+ + Fe 1.92 V
e1-e1-e1-e1-e1-e1-e1-
underground Fe tank
Mg
Fe2+ + 2e1- Fe - 0.45 VMg2+ + 2e1- Mg - 2.37 VMg Mg2+ + 2e1- - 2.37 VFe2+ + Mg Mg2+ + Fe 1.92 V
e1-
underground Fe tank
Mg
Fe2+ + 2e1- Fe - 0.45 VMg2+ + 2e1- Mg - 2.37 VMg Mg2+ + 2e1- - 2.37 VFe2+ + Mg Mg2+ + Fe 1.92 V
e1-
underground Fe tank
Mg
Fe2+ + 2e1- Fe - 0.45 VMg2+ + 2e1- Mg - 2.37 VMg Mg2+ + 2e1- - 2.37 VFe2+ + Mg Mg2+ + Fe 1.92 V
e1-
underground Fe tank
Mg
Fe2+ + 2e1- Fe - 0.45 VMg2+ + 2e1- Mg - 2.37 VMg Mg2+ + 2e1- - 2.37 VFe2+ + Mg Mg2+ + Fe 1.92 V
e1-
underground Fe tank
Mg
Fe2+ + 2e1- Fe - 0.45 VMg2+ + 2e1- Mg - 2.37 VMg Mg2+ + 2e1- - 2.37 VFe2+ + Mg Mg2+ + Fe 1.92 V
e1-
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