[Chemistry Class Notes] Iron Oxide Pdf for Exam

Iron oxide, which is also called ferric oxide, is an inorganic compound having the chemical formula Fe₂O₃. It is one of the 3 major oxides of iron, and the remaining two being iron(II) oxide (FeO), which is the rare iron (II, and III) oxide (Fe₃O₄), and also naturally takes place as the mineral magnetite. Since the mineral is referred to as hematite, Fe₂O₃ is iron’s primary source for the steel industry and is readily attacked by acids. Often, iron oxide can be referred to as rust. This label is useful to some extent because rust shares many properties and has the same composition. But, in chemistry, rust is considered an ill-defined material, which can be described as Hydrous ferric oxide.

 

Brief Explanation about Iron Oxide

Iron oxide is a compound made from iron and oxygen. There are 16 known iron oxides and oxyhydroxides, the most famous of which is rust, a type of ferric oxide. Iron oxides and oxyhydroxides are widespread and play important roles in many geological and biological processes. They are used in iron ore, pigments, catalysts, thermites and are contained in hemoglobin. Iron oxide is a cheap and permanent pigment found in paints, coatings, and colored concrete. Commonly available colors are on the “soil” edge of the yellow / orange / red / brown / black range. When used as a food coloring, the E number is E172.

 

Structure

Iron oxide Structure – Fe₂O₃

Iron oxide Structure – Fe₂O₃ 

 

()

 

Properties of Iron Oxide

 

Physical Properties

Physical Properties of Iron oxide – Fe2O3

 

Chemical Properties of Iron Oxide – Fe₂O₃         

[ Fe_{2}O_{3} + H_{2}O rightarrow Fe (OH)_{3}]

[ Fe_{2}O_{3} + H_{2}SO_{4} rightarrow Fe_{2} (SO_{4})_{3} + H_{2}O ]

Preparation of Iron Oxide

• Iron(III) oxide is the oxidation of the iron products, where it can be prepared in the laboratory by electrolyzing sodium bicarbonate solution, which is an inert electrolyte including an iron anode:

[ 4Fe + 3O_{2} + 2H_{2}O rightarrow 4 FeO(OH) ]

[ 2 FeO(OH) rightarrow Fe_{2}O_{3} + H_{2}O ]

 

Reactions

One of the most important reactions of iron oxides is its carbothermal reduction that gives iron, used in steel-making:

 

[ Fe_{2}O_{3} + 3CO rightarrow 2Fe + 3CO_{2} ]

 

The other redox reaction is with aluminum, which is an extremely exothermic thermite reaction.

 

[ 2 Al + Fe_{2}O_{3} rightarrow 2 Fe + Al_{2}O_{3} ]

 

We can use this process to weld the thick metals including rails of train tracks with the help of a ceramic container to funnel the molten iron in between 2 sections of the rail. Thermite can also be used in making small-scale cast-iron sculptures, weapons, and tools.

 

Partial reduction, along with the hydrogen compound at around 400 ⁰C will produce magnetite, which is referred to as a black magnetic material. It contains both Fe(III) and Fe(II):

 

[ 3 Fe_{2}O_{3} + H_{2} rightarrow 2 Fe_{3}O_{4} + H_{2}O ]

 

The Iron(III) oxide results in insoluble water, but it readily dissolves in strong acid. For example, sulfuric and hydrochloric acids. It also dissolves well in the solutions of chelating agents like oxalic acid and EDTA.

 

Heating the iron(III) oxide with other carbonates or metal oxides yields materials called ferrates (ferrate (III)):

 

[ ZnO + Fe_{2}O_{3} rightarrow Zn(FeO_{2})_{2}]

 

Uses of Iron Oxide – Fe₂O₃

• Common black iron oxide is used in both copper plates and stamp embossed inks. 

•  Iron oxide forms the main component of products in the pharmaceutical, paint, plastic, ink  and cosmetics industries. 

•  It is used as a naturally occurring pigment containing titanium dioxide. 

•  The salt is used as a flocculant in wastewater treatment, fiber dyeing, fertilizer and feed additive production. 

•  Used as an abrasive in the jewelry industry.

 

Other Uses of Iron Oxide Fe₂O₃

Let us look at the uses of iron oxide in various industries, listed below.

 

Iron Industry

The overwhelming iron(III) oxide application is the feedstock of the iron and steel industries. For example, the production of steel, iron, and several alloys.

 

Polishing

A very fine powder of the ferric oxide is called “red rouge,” “jeweler’s rouge,” or just as a rogue. It can be used to put the final polish on the lenses and metallic pieces of jewelry, and historically, as a cosmetic. This rouge cuts more slowly than a few modern polishes, like cerium(IV) oxide, but still, it is used by jewelers for the superior finish it can produce and in the optics fabrication. The rouge slightly stains the gold when polishing gold, which contributes to the appearance of the finished piece.

 

Pigment

Iron oxide can also be used as a pigment, under the names “Pigment Brown 6”, “Pigment Brown 7”, “Pigment Red 101”. A few of them as examples are Pigment Brown 6, Pigment Red 101, which are approved by the US Food & Drug Administration – FDA, for cosmetics use. In addition, iron oxides can be used as pigments in dental composites alongside titanium oxides.

 

Hematite is one of the characteristic components of the Swedish paint color Falu red.

 

Medicine

Calamine lotion, which is used to treat mild itchiness, is chiefly composed of a combination of zinc oxide, by acting as an astringent, and around 0.5% iron(III) oxide, the active ingredient of the product, acting as an antipruritic. The red color iron(III) oxide is also primarily and widely responsible for the familiar pink color lotion.