Chemical reactions of iron with simple and complex substances, and its role in human activity

Properties of iron

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Iron is the sec­ond most wide­spread met­al on Earth. It has a medi­um chem­i­cal ac­tiv­i­ty and is used by hu­mans in a wide range of ac­tiv­i­ties. It is met­al with mag­net­ic prop­er­ties.

Dis­tri­bu­tion of iron in na­ture

Many min­er­als con­tain iron – for ex­am­ple mag­netite is 72% iron. This min­er­al known as “mag­net­ic iron ore” is dark gray (al­most black) and has a char­ac­ter­is­tic metal­lic shine. Hematite is an­oth­er min­er­al with a high iron con­tent (up to 70%). This el­e­ment is known as “red iron ore”, and is dark red with a brown tinge to gray­ish-red.

Limonite is a min­er­al with an iron con­tent of 85%. This el­e­ment is a crys­tal hy­drate, which is yel­low, or more rarely brown. Limonite is known as “brown iron ore” and used as a pig­ment.

Disc-shaped, brown siderite crystals perched upon chalcopyrites [Wikimedia]

Siderite is a min­er­al known as “spath­ic iron ore”, and has an iron con­tent of 35%. The struc­ture of the el­e­ment is het­eroge­nous and con­sists of crys­tals of gray, yel­low and brown tinges.

Pyrite is a min­er­al with an iron con­tent of 47%. This el­e­ment has a yel­low-gold­en tinge be­cause of the sul­fur atoms present in it.

Many of the min­er­als list­ed above are used for the pro­duc­tion of pure iron. Iron is present in liv­ing or­gan­isms and is an im­por­tant com­po­nent of cells. For the prop­er func­tion­ing of the hu­man body, a suf­fi­cient amount of this mi­croele­ment must be con­sumed, which has a pos­i­tive ef­fect on the state of the blood.

Chem­i­cal prop­er­ties of iron

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Iron has prop­er­ties typ­i­cal for oth­er met­als (the ex­cep­tion is met­als in the elec­tro­chem­i­cal row to the right of hy­dro­gen). Iron en­ters into a re­ac­tion with sub­stances of dif­fer­ent class­es, and in­ter­acts with oxy­gen, car­bon, phos­pho­rus, halo­gens (bromine, io­dine, flu­o­rine and chlo­rine), and also ni­tro­gen. These are not all the re­ac­tions of iron – this met­al re­acts with many el­e­ments.

To ob­tain iron ox­ide, the met­al is burned, and the prod­ucts of this chem­i­cal re­ac­tion de­pend on the pro­por­tions of the el­e­ments par­tic­i­pat­ing. Ac­cord­ing­ly, the prop­er­ties of iron ox­ide dif­fer. This re­ac­tion can only be car­ried out at a high tem­per­a­ture.

The re­ac­tion be­tween iron and ni­tro­gen is also pos­si­ble with heat­ing. Chem­i­cal re­ac­tions with iron and phos­pho­rus form phos­phide, and iron also in­ter­acts with sul­fur, form­ing sul­fide (this takes place as a re­sult of a com­bi­na­tion re­ac­tion). Any chain re­ac­tion with iron and oth­er el­e­ments re­quires spe­cial con­di­tions – usu­al­ly high tem­per­a­tures, more rarely cat­a­lysts are used.

The in­ter­ac­tion be­tween iron and halo­gens is of­ten used in in­dus­try – the re­ac­tion of bromi­na­tion, chlo­ri­na­tion, flu­o­ri­na­tion and io­d­i­na­tion. This re­ac­tion takes place from the at­tach­ment of bromine, chlo­rine, flu­o­rine or io­dine atoms to iron atoms, with the sub­se­quent for­ma­tion of bro­mide, chlo­ride, flu­o­ride and io­dide. At high tem­per­a­ture, iron bonds with sil­i­con.

The di­verse chem­i­cal prop­er­ties of iron have giv­en rise to the wide ap­pli­ca­tion of the met­al in in­dus­try, which it is hard to imag­ine with­out the ex­is­tence of iron.

Click here to see amaz­ing ex­per­i­ments with iron.

In­ter­ac­tion of iron with com­plex sub­stances

It is worth dis­cussing the in­ter­ac­tion of iron with sub­stances whose mol­e­cules con­sists of at least two el­e­ments. On the in­ter­ac­tion of in­can­des­cent iron with wa­ter, an ox­i­diz­ing re­ac­tion takes place, as a re­sult of which a ba­sic ox­ide forms. The re­sults of in­ter­ac­tion will de­pend on the pro­por­tions of com­po­nents – if you take 4 moles of wa­ter and 3 moles of iron, you will get hy­dro­gen (gas with a harsh smell) and iron cin­der.

The re­ac­tion of iron with salts and acids is also car­ried out. Iron forces hy­dro­gen out of com­pounds by a dis­place­ment re­ac­tion. You can ob­serve it by adding acid to iron. For ex­am­ple, when you mix di­lut­ed sul­fu­ric acid and iron in iden­ti­cal mo­lar pro­por­tions, hy­dro­gen and iron sul­fate form in iden­ti­cal mo­lar pro­por­tions.

An­oth­er ex­am­ple of the dis­place­ment re­ac­tion:

The in­ter­ac­tion with salts demon­strates that iron has re­duc­ing prop­er­ties. With the use of iron, the less ac­tive met­al is forced out of a salt. Ex­am­ple: if you mix one mole of iron and one mole of cop­per sul­fate, the re­sult is pure cop­per and iron sul­fate in equal mo­lar pro­por­tions.

Iron and its im­por­tance for the hu­man body

Iron per­forms im­por­tant func­tions at cel­lu­lar lev­el; this el­e­ment is the ba­sis for he­mo­glo­bin, with­out which trans­porta­tion of oxy­gen in the blood from the lungs to the brain neu­rons and to all the tis­sues in the body would be im­pos­si­ble. Iron in­flu­ences blood for­ma­tion, and with­out it the thy­roid gland would not work prop­er­ly. Iron reg­u­lates the im­mu­ni­ty and takes part in in­ter­cel­lu­lar me­tab­o­lism, and many en­zymes in the hu­man body would not form with­out it. To avoid suf­fer­ing from a deficit of iron, peo­ple should reg­u­lar con­sume prod­ucts con­tain­ing this mi­croele­ment.

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How iron is pro­duced for in­dus­try

Met­al is main­ly pro­duced from min­er­als – hematite and mag­netite. This is done by re­duc­ing iron from its com­pounds with car­bon in the form of coke. The process takes place in blast fur­naces at a tem­per­a­ture of 2,000 °C. The method of re­duc­ing iron by hy­dro­gen is also used – spe­cial clay is re­quired, which is mixed with crushed ore and pro­cessed with hy­dro­gen from a shaft fur­nace.

Iron is wide­spread across the en­tire plan­et and com­pris­es up to 5% of the earth’s crust. It is be­lieved that the ma­jor­i­ty of the earth’s core con­sists of iron.