Rust
(→What is rust?) |
(→What is rust?) |
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Iron, with the chemical symbol of Fe, combines with oxygen, O, to form Fe<sub>2</sub>O<sub>3</sub>, the chemical formula for common reddish-brown rust. In its mineral form, this is known as hematite. | Iron, with the chemical symbol of Fe, combines with oxygen, O, to form Fe<sub>2</sub>O<sub>3</sub>, the chemical formula for common reddish-brown rust. In its mineral form, this is known as hematite. | ||
| − | Rust is commonly referred to as ''iron oxide''. An oxide is a type of chemical compound that contains oxygen and other elements (like nitrous oxide, N<sub>2</sub>O). Oxides are typically formed when elements come into contact with air, through a process known as oxidation. Oxides are common, forming most of the earth's crust. Elements can have multiple oxides. For example, there are sixteen known iron oxides. Thus, it's more accurate to say that rust is '''an''' iron oxide. | + | Rust is commonly referred to as ''iron oxide''. An oxide is a type of chemical compound that contains oxygen and other elements (like nitrous oxide, N<sub>2</sub>O). Oxides are typically formed when elements come into contact with air, through a process known as oxidation. Oxides are common, forming most of the earth's crust. Elements can have multiple oxides. For example, there are sixteen known iron oxides. Thus, it's more accurate to say that rust is '''an''' iron oxide, rather than saying that rust '''is''' iron oxide. |
Other metals besides iron 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. However, only the oxidation of iron and steel 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 reddish-brown color, that is very different from steel: it's reddish-brown. | Other metals besides iron 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. However, only the oxidation of iron and steel 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 reddish-brown color, that is very different from steel: it's reddish-brown. | ||
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