Third group of cations iron ll and III , aluminium lll

Group reagent hydrogen sulphide (gas or saturated aqueous solution) in the presence of ammonia and ammonium chloride, or ammonium sulphide solution. 

Group reaction precipitates of various colours iron(II) sulphide (black), aluminium hydroxide (white), chromium(III) hydroxide (green), nickel sulphide (black), cobalt sulphide (black), manganese(II) sulphide (pink), and zinc sulphide (white). 

Chemically pure iron is a silver-white, tenacious, and ductile metal. It melts at 1535°C. The commercial metal is rarely pure and usually contains small quantities of carbide, silicide, phosphide, and sulphide of iron, and some graphite. These contaminants play an important role in the strength of iron structures. Iron can be magnetized. Dilute or concentrated hydrochloric acid and dilute sulphuric acid dissolve iron, when iron(II) salts and hydrogen gas are produced. 

concentrated sulphuric acid yields iron(III) ions and sulphur dioxide 2Fe -F 3H2SO4 -F 6H+ 2Fe + -F 3SO2T + 6H2O With cold dilute nitric acid, iron(II) and ammonium ions are formed  

concentrated nitric acid renders iron passive, in this state it does not react with dilute nitric acid nor does it displace copper from an aqueous solution of a copper salt. 8m or hot, concentrated nitric acid dissolves iron with the formation of nitrogen oxide gas and iron(III) ions  

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