Rust
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==What is rust?== | ==What is rust?== | ||
| − | Rust is the common name for iron oxide. An oxide is a chemical compound containing an oxygen atom and other elements. Oxides are formed when elements come into contact with air, through a process known as oxidation. Oxides are common, forming most of the earth's crust. When iron (or steel, which contains mostly iron) is exposed to air, it combines with the oxygen in the air, and forms iron oxide | + | Rust is the common name for '''an''' iron oxide. An oxide is a chemical compound containing an oxygen atom and other elements. Oxides are formed when elements come into contact with air, through a process known as oxidation. Oxides are common, forming most of the earth's crust. When iron (or steel, which contains mostly iron) is exposed to air, it combines with the oxygen in the air, and forms the iron oxide known as rust. |
Rust is iron plus oxygen. | Rust is iron plus oxygen. | ||
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Other metals oxidize, but their oxidation is not referred to as rust. For example, when aluminum oxidates, it forms a protective, corrosion-resistant coating that looks a lot like un-oxidized aluminum. Zinc's oxide is similar, which is why it is used for galvanizing. | Other metals oxidize, but their oxidation is not referred to as rust. For example, when aluminum oxidates, it forms a protective, corrosion-resistant coating that looks a lot like un-oxidized aluminum. Zinc's oxide is similar, which is why it is used for galvanizing. | ||
| − | Only the oxidation of iron and steel (iron oxide) is known as "rust". Why? Because iron oxide takes up more physical space than iron. It's bigger. So, when iron pulls oxygen atoms from the air, to make iron oxide, it "puffs out", exposing even more of the original steel to the elements. And, it has a distinct color, that is very different from steel: it's | + | Only the oxidation of iron and steel (iron oxide) is known as "rust". Why? Because iron oxide takes up more physical space than iron. It's bigger. So, when iron pulls oxygen atoms from the air, to make iron oxide, it "puffs out", exposing even more of the original steel to the elements. And, it has a distinct color, that is very different from steel: it's reddish-brown. |
Iron is FE, although it rarely exists in pure form. Oxygen is O2. They combine to form FE2O3: one of 16 possible known iron oxides. | Iron is FE, although it rarely exists in pure form. Oxygen is O2. They combine to form FE2O3: one of 16 possible known iron oxides. | ||
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