Physical Properties
Pure iron is a grey white metals. It appears to be brown due to rusting. It is malleable, ductile and magnetic. A good conductor of heat and electricity. Iron has a high density and high melting point.Chemical Properties
Valency
A transition element and there-fore shows variable valency. It shows valency of +2 and forms divalent ions Fe2+ (ferrous ions) and valency of +3 and forms trivalent ions Fe3+ (ferric ions). The compounds of divalent ions are called ferrous compounds and trivalent ions are called ferric compounds.
Reaction with Oxygen
Iron does not combine with oxygen in ordinary temperature. When it is strongly heated in air, it forms a black compound called iron (II,III) oxide.
Iron rusts in damp air forming a brown mixture of iron (III) oxide Fe2O3 and iron (III) hydroxide Fe(OH)3 on its surface. This mixture is called rust.
Reaction with Water
Iron does not react with water in the ordinary temperature. It reacts only with steam. When steam is passed over red-hot iron, iron (II,III) oxide and hydrogen gas are formed.
Reaction with Acids
Iron displaces hydrogen from dilute acids and forms iron salts.
Iron reacts with dilute sulphuric acid to form iron sulphate and hydrogen.
Iron reacts with concentrated sulphuric acid to give iron (III) sulphate, SO2 and H2.
Iron reacts with dilute nitric acid to form iron (II) nitrate and ammonium nitrate
Conc. Nitric acid renders iron passive due to formation of thin layer of ferric oxide.
Passivity can be removed by strongly heating the metal.Reaction with non-metals
Iron forms ferric chloride when heated with chlorine.
Iron forms ferrous sulphide when heated with sulphur.
Displacement Reaction
Iron displaces metals like copper and silver from their metallic salt solutions.
