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Iron(II) oxide

Adapted from Wikipedia · Discoverer experience

A sample of Iron(II) oxide, a common black powder used in science and industry.

Iron(II) oxide, also called ferrous oxide, is a chemical compound with the formula FeO. It is found in nature as a mineral called wüstite. This compound is one of several types of iron oxides and looks like a black powder. People often mistake it for rust, but rust is actually a different substance called hydrated iron(III) oxide.

Iron(II) oxide can also refer to a group of similar compounds that do not have exactly the same ratio of iron to oxygen. These compounds usually have a bit less iron than the simple FeO formula, with amounts ranging from Fe0.84O to Fe0.95O. This compound is important in many industrial processes and is used in making different products.

Occurrence

Iron(II) oxide is found in about 9% of Earth's mantle. In this layer, it might help conduct electricity, which could explain some changes in Earth's spinning that current theories don't fully understand.

Structure

Iron(II) oxide has a special shape called cubic, similar to rock salt. In this shape, iron atoms are surrounded by oxygen atoms, and oxygen atoms are surrounded by iron atoms. Sometimes, a few iron atoms change their form, which makes the structure a bit different.

When melted, iron atoms are mostly surrounded by four or five oxygen atoms. At very cold temperatures, below 200 K, the structure changes slightly and the material behaves in a special magnetic way.

Preparation

Iron(II) oxide, or FeO, can be made by heating iron(II) oxalate. This process creates FeO along with carbon dioxide and carbon monoxide. It is important to do this in a special environment that does not let air in, so that another form of iron oxide does not form.

Another way to make FeO is by heating a special mix of iron and oxygen at high temperature and pressure. This method also helps create the exact amount needed. The same idea can be used to make other oxides, like manganous oxide and stannous oxide.

Uses

Iron(II) oxide is used as a pigment. It is approved by the FDA for use in cosmetics and in some tattoo inks. It can also help remove phosphates from home aquariums.

Reactions

Iron(II) oxide, or FeO, is not very stable when it is below a temperature of 575 °C. At this lower temperature, it tends to break down into iron metal and another compound called Fe3O4. This can be shown by the equation:

4 FeO → Fe + Fe3O4

Images

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A 3D model showing the crystal structure of Manganese(II) oxide, a mineral compound.
A 3D model showing the structure of nitrous oxide, a chemical compound, using colored balls and sticks to represent its atoms and bonds.
A 3D model showing the structure of ethanol molecules using colored balls and sticks.
A 3D model of Buckminsterfullerene, a unique form of carbon shaped like a soccer ball.
A stunning view of Earth rising over the lunar horizon, as seen by astronauts during the Apollo 8 mission.

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This article is a child-friendly adaptation of the Wikipedia article on Iron(II) oxide, available under CC BY-SA 4.0.

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