Iron oxide

Iron oxide
General
Other names	Ferric oxide Hematite
Molecular formula	Fe2O3
Molar mass	molar mass::159.69 g/mol
Appearance	red-brown solid
CAS number	CAS number::1317-60-8 [1309-37-1] [1309-37-1](Iron Oxide Red)
Properties
Density and phase	[[Density::5.24 g/cm3]], solid
Solubility in water	insoluble
Melting point	Melting point::1566 °C decomp.
Structure
Crystal structure	rhombohedral
Related compounds
Other anions	Iron(II) sulfide Iron(II) oxide Iron(II,III) oxide
Other cations	Ruthenium(IV) oxide Osmium(IV) oxide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Disclaimer and references

Iron(III) Oxide is one of the oxide compounds of iron, which has the chemical formula Fe₂O₃. It has many different names and some of the most common names it is called is hematite, rust, ferric oxide, and colcothar. This compound occurs when minerals and rocks containing minerals react with the oxygen that is in the air and this compound has many different uses.

Properties

Iron oxide is also known as Rust

Iron Oxide has many different forms. Some of the phases are the Alpha phase, the Beta phase, Gamma phase, and the Epsilon phase.

In the Alpha phase, its most common form is as a Rhombohedric, and its occurrence is as the mineral hematite. It is ferromagnetic at all times except for at low temperatures, when it is then antiferromagnetic. Depending on many different factors, like particle size, magnetic field intensity, and pressure, its magnetic properties are different. You can also easily prepare this in the liquid phase using both the precipitation and the thermal decomposition phases.

The Beta phase is cubic face centered or metastable. This can be converted to the alpha phase when it is heated at any temperature over 500 °C.

The Gamma phase is cubic, metastable, and can also be converted to the alpha phase by using high temperatures. The natural occurrence of the gamma phase happens as the mineral maghemite.

The Epsilon phase is rhombic and has properties in between the alpha and the gamma phases. It has never been prepared in pure form yet since it has always been mixed with the alpha phase or gamma phases.[1]

Occurrences

A piece of Hematite

The natural way that Hematite occurs is when mineral and rocks containing minerals react with the oxygen that is in the air. This forms iron(III), and through many different procedures, it can also be made synthetically. In most common way of creating this synthetically, iron(II) sulfate is made to react with sodium hydroxide (NaOH) to make iron(II) hydroxide [Fe(OH)2]. This is then made to react with oxygen from the air, which then produces iron(III) oxide. Another way that this compound can be created is by heating up iron(II) sulfate, iron(III) oxalate [Fe2(C2O3)3] , or hydrated iron(II) oxide [FeO(OH)].[2]

Uses

A bagcharm containing Hematite beads

There are many different uses for Iron Oxide. It is used in making jewelry, magnetic storage, pigments, and for polishing.

Magnetic Storage:

One example that iron(III) oxide is used in magnetic storage is in floppy disks. It is used in the magnetic layer which are made up of thin sheets of PET film. This PET film is then coated with iron(III) oxide and the particles in it can represent binary data by being magnetised. Another area that iron(III) oxide is used in is in ink. The compounds can be suspended in the ink which makes special scanning hardware able to read it.

Pigments:

Another use for iron(III) oxide is in pigments. There are several different pigments that it can be found in, some of which have been approved for makeup by the FDA. [3]

Interesting Facts

• Small particles that are thought to be hematite were found by NASA’s Mars rover Opportunity on the surface of the planet Mars. It is thought by scientists that these particles had formed billions of years ago when Mars had water on its surface.
• One of Iron(III) oxide’s names is “hematite”, which came from the Greek word for blood.
• 40,000 years ago, Paleolithic humans in Swaziland mined hematite to produce a red colored pigment called ochre. They did this in the Lion Cave, which, according to the archaeological record, is the oldest mine known.
• Hematite can be made into an ornament, and when done so, it is sometimes called “black diamond[4]

Names

There are a variety of names for Hematite or Iron Oxide. Some of the names are due to different gems since many of them have their red color and other characteristics due to the presence of hematite in them. Some of the other names for Iron Oxide are:

• Black diamond
• Blood stone
• Alaskan diamond or Alaskan black diamond
• Rainbow hematite
• Iridescent specularite
• Drusy hematite [5]
• Ferric oxide
• Red iron oxide
• Synthetic maghemite
• Colcothar
• Rust[6]

References

• Wikipedia
• Iron(iii) Oxide BookRags.
• HEMATITE GemRocks: Hematite.

See Also

• Thermite