Corrosion of iron

The film shows corrosion of iron over three days. When iron corrodes, it is called rust. The reaction is quite complicated but involves iron combining with oxygen with the help of water-all three ingredients are necessary. Initially, iron forms iron ions through oxidation: 4Fe becomes 4Fe^3+ + 12e-. Oxygen molecules O2 and water H2O are reduced by taking up electrons and forming hydroxide ions OH-: 3O2 + 12e- + 6H2O become 12OH-. Finally, iron(III) hydroxide, what we call rust, is formed, according to 4Fe^3+ + 12OH- becoming 4Fe(OH)3.
Read more about chemistry, metals, and corrosion in the textbook 'chemistry 9' by Kaj Schmidt, which you can find on Apple Books.