| Reactions of Iron |
 Reactions with water |
| Air-free water has little effect upon iron metal. However, iron metal reacts in moist air by oxidation to give a hydrated
iron oxide. This does not protect the iron surface to further reaction since it flakes off, exposing more iron metal to oxidation.
This process is called rusting!
|
| Reactions with air |
| Iron metal reacts in moist air by oxidation to give a hydrated iron oxide. This does not protect the iron surface to further
reaction since it flakes off, exposing more iron metal to oxidation. This process is called rusting. Finely divided iron powder
is pyrophoric, making it a fire risk.
|
| On heating with oxygen the result is formation of the iron oxides Fe2O3 and Fe3O4.
|
4Fe(s) + 3O2(g) 2Fe2O3(s) |
| 3Fe(s) + 2O2(g)2Fe3O4(s) |
| Reactions with halogens |
| Iron reacts with excess of fluorine, chlorine and bromine to form Fe(III) halides.
|
| 2Fe(s) + 3F2(g)2FeF3(s) |
| 2Fe(s) + 3Cl2(g)2FeCl3(s) |
| 2Fe(s) + 3Br2(g)2FeBr3(s) |
| This reaction is not very successful for iodine because of thermodynamic problems. The iron(III) is too oxidizing and the iodide is too reducing. The direct reaction between
iron and iodine can be used to prepare iron (II) iodide.
|
| Fe(s) + I2(s)FeI2(s) |
| Reactions with acids |
| Iron metal dissolves readily in dilute sulphuric acid in the absence of oxygen to form solutions containing the aquated Fe(II) ion together with hydrogen gas.
|
| Fe(s) + H2SO4(aq)Fe2+(aq) + SO42-(aq) + H2(g) |
| If oxygen is present, some of the Fe(II) oxidizes to Fe(III).
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| The strongly oxidizing concentrated nitric acid, HNO3, reacts on th surface of iron and passivates the surface.
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Fe(s)