Iron’s interactions with water and oxygen

Chemical properties of iron

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Iron is a met­al in the eighth group, fourth pe­ri­od of the pe­ri­od­ic ta­ble. Its sym­bol is Fe. Its atom­ic num­ber is 26 and molec­u­lar weight‎ is 56 g/mol. The met­al has medi­um ac­tiv­i­ty and is a re­duc­er.

Iron is sil­very-white and very mal­leable, with a melt­ing point of 1539°С. When heat­ed, it quick­ly gains elas­tic­i­ty and can be forged and worked. More­over, when heat­ed, it can re­act with wa­ter and oxy­gen.

Preva­lence of iron on Earth

Iron is one of the most wide­spread el­e­ments on Earth, oc­cu­py­ing fourth place af­ter alu­minum, oxy­gen, and sil­i­con. The earth’s crust is ap­prox­i­mate­ly 5% iron. Many min­er­als, such as mag­netite, hematite, pyrite, and limonite, con­sist most­ly of iron.

Phys­i­cal prop­er­ties of iron


Iron is used in elec­tri­cal de­vices for its mag­net­ic prop­er­ties and elec­tri­cal con­duc­tiv­i­ty. There are two types of iron:

  1. pure;
  2. com­mer­cial­ly pure.

Pure iron con­tains a min­i­mum of im­pu­ri­ties. Com­mer­cial­ly pure iron can con­tain up to 0.1% car­bon, oxy­gen, ni­tro­gen, sul­fur, and, in even small­er quan­ti­ties, phos­pho­rus. Pure iron re­sem­bles plat­inum – sil­very and shiny. Com­mer­cial­ly pure iron does not cor­rode and is min­i­mal­ly af­fect­ed by acids. It is flex­i­ble and elas­tic.

Chem­i­cal prop­er­ties of iron

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Iron swift­ly ox­i­dizes (rusts) in the pres­ence of mois­ture. The re­ac­tion is:

4Fe + 3O₂ + 6H₂O = 4Fe(OH)₃

When heat­ed, iron re­acts with wa­ter to form its main ox­ide. Com­bin­ing 3 moles of iron and 4 moles of wa­ter will re­sult in iron ox­ides with a non-sto­i­chio­met­ric com­po­si­tion of FeₓOᵧ – mixed iron(II,III) ox­ide Fe₃O₄ and gaseous hy­dro­gen. The re­ac­tion be­tween iron and wa­ter pro­ceeds ac­cord­ing to the fol­low­ing equa­tion:

3Fe + 4H₂O = Fe₃O₄ + 4H₂↑

Sample of magnetite, naturally occurring Fe₃O₄ [Wikimedia]

These sub­stances are wide­ly used in in­dus­try and oth­er fields.

Click here for safe and en­ter­tain­ing ex­per­i­ments with iron.

Re­ac­tion of iron with oxy­gen

Iron re­acts with oxy­gen only when heat­ed. This can be demon­strat­ed via the fol­low­ing ex­per­i­ment. Hold a fine iron wire over a burn­er flame. Then plunge the in­can­des­cent wire into a con­tain­er of oxy­gen. The wire will burn with a bright flame and emit sparks. These sparks are par­ti­cles of iron cin­der Fe₃O₄. A sim­i­lar re­ac­tion also takes place in the air, when steel is heat­ed via fric­tion:

3Fe + 2O₂ = Fe₃O₄


3Fe + 2O₂ = FeO•Fe₂O₃

These re­ac­tions in­volve a re­lease of heat and light en­er­gy.

Iron in ev­ery­day life


Iron’s above­men­tioned chem­i­cal prop­er­ties and re­ac­tions with var­i­ous el­e­ments are wide­ly ap­plied in prac­tice. For ex­am­ple, steel and cast-iron are made of iron. Steel con­tains less than 2.14% car­bon, and cast-iron not more than 7% car­bon. Cast-iron is used in build­ing ma­te­ri­als, ma­chine parts, the au­to­mo­bile in­dus­try, rails, and tools.

Pure iron is used in the man­u­fac­ture of trans­form­ers and elec­tro­mag­nets. Iron is un­doubt­ed­ly one of the most cru­cial el­e­ments to hu­man life. Prac­ti­cal­ly ev­ery­thing is made from it nowa­days. It has re­placed bronze in the pro­duc­tion of tools. And iron al­loys have more use­ful prop­er­ties than al­loys of cop­per and tin, es­pe­cial­ly con­sid­er­ing its abun­dance on Earth in com­par­i­son to oth­er met­als. This el­e­ment is also a com­po­nent of he­mo­glo­bin, which is vi­tal to the func­tion­ing of the hu­man body. In gen­er­al, iron plays a crit­i­cal role in main­tain­ing the health of the en­tire body and the nor­mal func­tion­ing of all or­gans and sys­tems.