Iron

Properties and Applications of Iron

Appearancelustrous metallic with a grayish tinge
Standard atomic weight A(Fe)55.845(2)[1]
Atomic number (Z)26
Groupgroup 8
Periodperiod 4
Blockd-block
Element category  transition metal
Electron configuration[Ar] 3d6 4s2
Electrons per shell2, 8, 14, 2


Iron has an atomic number 26 with an element symbol Fe (Ferrum) and it’s the first metal of the transition series.Not only Iron can be easily found on the earth core and the surface of it but also it is the most common metal on the earth surface. In addition, from all the other metal from the list, Iron is the fourth common element found on the earth surface.

Like the other groups 8 elements, ruthenium and osmium, iron exists to have in a wide range of oxidation states, −2 to +7, although +2 and +3 are the more common. Elemental iron occurs in shooting stars and other less oxygen environments, but it gets charged up with oxygen and water. Fresh iron surfaces appear shinny silvery-gray but oxidize in standard air environment to give hydrated iron oxides, most commonly known as rust. Unlike the metals that form passivity oxide layers, iron oxides occupy supplementary volume than the metal and thus flake off, exposing fresh surfaces production for corrosion.

Industrial routes


The production of iron or steel is a process done in two main stages. In the first stage pig iron is created in a blast furnace. On the other hand, it may be directly reduced. In the second stage, pig iron is transformed to wrought iron, steel, or cast iron.
For a limited method when it is needed, pure iron is produced in the laboratory in less quantities by reducing the amount of pure oxide or hydroxide with hydrogen or forming iron pent carbonyl and heating it to 250 °C so that it decomposes to form pure iron powder. Other method is electrolysis of ferrous chloride onto an iron cathode

Blast furnace processing


Industrial iron making starts with iron ores, principally hematite, which has a nominal formula Fe2O3, and magnetite, with the formula Fe3O4. These ores are reduced to the metal by treatment with carbon which is called as carbothermic reaction. The adaptation is typically conducted in a blast furnace at temperatures of about 2000 °C. Carbon is provided in the form of coke. The process also contains a flux such as limestone, which is used to eliminatesiliceous minerals in the ore, which would otherwise clog the furnace. The coke and limestone are fed into the top of the furnace, while a massive blast of air heated to 900 °C, about 4 tons per ton of iron,[116] is forced into the furnace at the bottom.

In the furnace, the coke reacts with O2 in the air blast to create CO (Carbon monoxide):

2 C + O2 → 2 CO

The carbon monoxide reduces the iron ore (in the chemical equation below, hematite) to molten iron, transforming to carbon dioxide in the process:

Fe2O3 + 3 CO → 2 Fe + 3 CO2


Some iron at high temperature bottom part of the furnace reacts directly with the coke:

2 Fe2O3 + 3 C → 4 Fe + 3 CO2


The flux that tries to melt impurities in the ore is principally limestone (calcium carbonate) and dolomite (calcium-magnesium carbonate). Other fluxes are used on the details of the ore. At thehigh temperature of the furnace the limestone flux decomposes to calcium oxide (also known as quicklime):

CaCO3 → CaO + CO2


Then calcium oxide mixes with silicon dioxide to create a liquid slag.

CaO + SiO2 → CaSiO3


The slag dissolve sat the high temperature of the furnace. In the base of the furnace, the molten slagfloats on top of the denser molten iron and apertures in the corner of the furnace are opened to run off the iron and the slag individually. The iron, once cooled, is called pig iron, while the slag material can be used in road construction or to improve mineral-poor soils for agriculture.

Direct iron reduction


Due to environmental concerns, other methods of producing iron have been developed. 

Two major reactions contain the direct reduction process:


Natural gas is to some extent oxidized (with heat and a catalyst):

2 CH4 + O2 → 2 CO + 4 H2


Iron ore is next treated with the gases in a furnace, creating solid sponge iron:

Fe2O3 + CO + 2 H2 → 2 Fe + CO2 + 2 H2O

Silica is discarded by adding a limestone flux as described above.

Characteristics


Physical properties
Phase at STPsolid
Melting point1811 K ​(1538 °C, ​2800 °F)
Boiling point3134 K ​(2862 °C, ​5182 °F)
Density (near r.t.)7.874 g/cm3
when liquid (at m.p.)6.98 g/cm3
Heat of fusion13.81 kJ/mol
Heat of vaporization340 kJ/mol
Molar heat capacity25.10 J/(mol·K)
Vapor pressure


Mechanical properties


The properties of iron and its alloys can be simplified using a variety of tests, including the Brinell test, Rockwell test and the Vickers hardness test. The data on iron is so reliable that it is often used to calibrate to compare tests. Nevertheless, the mechanical properties of iron are drastically affected by the different results of purity: pure, individual crystals of iron are less hard than aluminum,and the purest industrially produced iron (99.99%) has a toughness of 20–30 Brinell. An increasing in the amount of carbon content will cause a significant increase in the toughness and tensile strength of iron. Highest hardness of 65 Rc is achieved with a 0.6% carbon content, although the alloy has low tensile strength. Due to the softness of iron, it is much simpler to work with than its heavier congeners ruthenium and osmium. According to which its significance for environmental cores, the physical properties of iron at high pressures and temperatures have also been studied widely. The form of iron that is steady under normal conditions can be subjected to pressures up to 15 GPa before ittransform into a high-pressure form, as described in the next section.

Chemistry and compound


Iron shows different attributeof chemical properties of the transition metals, namely the tendency to form variable oxidation states differentiated by steps of one and a very large coordination and organometallic chemistry: certainly, it was the discovery of an iron compound, ferrocene, that revolutionized the latter field in the 1950s. Sometimes iron considered as a prototype for the entire building block of transition metals, due to its loads and the immense role it has played in the technological progress of humanity. In its configuration 26 elements are arranged [Ar]3d64s2, of which the 3d and 4s electrons are close in energy.
It forms compounds mainly in the +2 and +3 oxidation states. Usually, iron (II) compounds called ferrous, and iron(III) compounds ferric. It also occurs in top oxidation states, e.g. the purple potassium ferrate (K2FeO4), which has iron in its +6-oxidation state. Although iron(VIII) oxide (FeO4) has been claimed, the result could not be produced again and such a species (at least with iron in its +8-oxidation state) has been found to be unlikely computationally. But, one form of anionic [FeO4] with iron in its +7-oxidation state, along with an iron(V)-peroxo isomer, has been found by infrared spectroscopy at 4 K after co condensation of laser-ablated Fe atoms with a mixture of O2/Ar.Iron (IV) is a general intermediate in many biochemical oxidation reactions. Numerousorgano iron compounds have formal oxidation states of +1, 0, −1, or even −2. The oxidation states and other bonding properties are often studied using the technique of Mössbauer spectroscopy.Many mixed valence compounds contain togetheriron (II) and iron (III) centers, such as magnetite and Prussian blue (Fe4(Fe [CN]6)3).The last is used as the traditional "blue" in blueprints.

Iron stands first of the transition metals that isunable to reach its group oxidation state of +8, although its heavier congener’s ruthenium and osmium can, with ruthenium having more difficulty than osmium. Ruthenium exhibits an aqueous cationic chemistry in its low-down oxidation states parallel to that of iron, but osmium does not, favoring high oxidation states in which it forms anionic complexes. In the other half of the 3d transition series, vertical similarities least on the groups compete with the horizontal similarities of iron with its neighbor’s cobalt and nickel in the periodic table, which are ferromagnetic at room temperature and contribute to similar chemistry. As such, iron, cobalt, and nickel are sometimes combined as the iron triad.

Applications


Iron is used in various sectors such as electronics, manufacturing, automotive, and construction and building.

The following are the application areas of iron:


  • • As the main constituent of ferrous metals/alloys and steels

  • • Combine with carbon, nickel, chromium and various other elements to form cast iron or steel

  • • In magnets

  • • In fabricated metal products

  • • In industrial machinery

  • • In transportation equipment

  • • In instruments

  • • In toys and sport goods