Reactions of Group 3 Cations

REACTIONS OF GROUP III CATIONS 1. Reactions of ferrous iron, Fe2+ 1. To a little of the salt solution A dirty green precipitate Ferrous hydroxide is precipi- ammonium chloride and excess tated. FeSO+2NH2OH ammonium hydroxide are added. Ferrous ferricyanide (Turn- 2. To a little of the salt solution A deep blue colour or precipi- bull's blue) formed is deep blue potassium ferricyanide solution tate is formed. in colour33eSO,+2K,[Fe(CN),J is added. Fe,[Fe(CN),]2++3K,SO, Pink colour of potassium per- Potassium permanganate is reduced 3. To a little of the salt solution manganate is discharged. tocolourless manganous sulphate. dil. H2SO4 4 and a few drops of 2KMnO + 10FeSO, + 8H,SO, KMnO4 are added. K,SO + 2MnSo+ 5Fe,(SO) + 8 H2O .

2. Reactions of Ferric iron, Fe3+ 1. To a little of the salt solution A reddish brown precipitate Ferric hydroxide is precipitated. ammonium chloride and excess is formed FeCl, + 3NH2OH of ammonium hydroxide are Fe(OH),+3NH,C added. 2. To a little of the salt solution po- A blood red colouration is This is due to the formation of tassium sulphocyanide (potassium obtained. ferric sulphocyanide.FeCl, + thiocyanate) solution is added. 3KCNS Fe(CNS),+3K 3. To a little of the salt solution A deep blue colouration is This is due to the formation of obtained. ferric ferrocyanide (Prussian blue) potassium ferrocyanide solution is added. 4FeCl + 3K,[Fe(CN),] Fe[Fe(CN)],+12KCI 3. Reactions of Aluminium, Al - A White gelatinous precipi- Aluminium hydroxide is precipi- 1. To a little of the substance am- tated. monium chloride and excess of tate is obtained. Al(NO) +3NH2OH ammonium hydroxide are Al(OH),+3NH,NO, added. 2. To a little of the salt solution, A white precipitate soluble in Aluminium hydroxide formed is NaOH solution is added drop by excess of sodium hydroxide soluble in excess of NaOH drop till in excess. is formed. solution.Al(NO1)3+3NaOH Al(OH)3 I+3NaNO3 Al(OH),+3NaOH 3. Ash test : To about 2ml of the Na,AIO,+3H2O A Blue ash is obtained. This is due to the formation of salt solution, one or two drops double oxide of cobalt and of conc. HNO and a little co- aluminium. balt nitrate solution are added. It is boiled and a filter paper dipped in it is burnt to ashes.