Rust is an iron oxide, a usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Several forms of rust are distinguishable both visually and by spectroscopy, and form under different circumstances. Rust consists of hydrated iron(III) oxides Fe2O.Iron oxide is formed when iron and oxygen react in the presence of water or moisture in the air. Iron oxide is very common, because iron reacts easily with oxygen in the air. ... Rust occurs when iron or its alloys, such as steel, corrode.as it is gets to corrode,it is called as corrosion Several forms of rust are distinguishable visually and by spectroscopy, and form under different circumstances.Rust consists of hydrated iron(III) oxides Fe2O3. nH2O, iron(III) oxide-hydroxide (FeO(OH), Fe(OH)3.It occurs when Iron, Oxygen and Water (air moisture) combine. ... When they combine, the iron loses electrons to oxygen atoms. This is called oxidation and when it happens it produces a chemical reaction forming Fe203 Iron Oxide otherwise known as Ferric Oxide, or more commonly known as rust.The chemical equation in words is-- iron plus water plus oxygen forms rust. In symbols, it is 4(Fe)+ 6 H2O+ 3 O2 forms 4Fe(0H)3 which is rust. Copper reacting with oxygen will produce copper oxide. The chemical equation is 4Cu+ 02 forms 2Cu20.