Page 244 - Chemistry ICSE Class X
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230 ICSE Chemistry – 10
Solubility
Metal salt + Ammonium o Ammonium salt + Metal hydroxide in excess
solution hydroxide precipitate ammonium
hydroxide
FeCl (aq) + 3NH OH(aq) o 3NH Cl(aq) + Fe(OH) (s) Insoluble
3
4
3
4
iron(III) chloride ammonium hydroxide iron(III) hydroxide (brown)
FeSO (aq) + 2NH OH(aq) o (NH ) SO (aq) + Fe(OH) (s) Insoluble
4
4 2
4
4
2
iron(II) sulphate ammonium hydroxide ammonium sulphate iron(II) hydroxide (light-green)
CrCl (aq) + 3NH OH(aq) o 3NH Cl(aq) + Cr(OH) (s) Insoluble
3
3
chromium(III) chloride 4 4 chromium(III) hydroxide (green)
Al(OH) (s)
3
AlCl (aq) + 3NH OH(aq) o 3NH Cl(aq) + aluminium(III) hydroxide Insoluble
4
4
3
aluminium(III) chloride (white-gelatinous)
ZnCl (aq) + 2NH OH(aq) o 2NH Cl(aq) + Zn(OH) (s) Soluble
2
2
zinc(II) chloride 4 4 zinc(II) hydroxide (white)
Zn(OH) (s)
2
Zn(NO ) (aq) + 2NH OH(aq) o 2NH NO(aq) + zinc hydroxide Soluble
4
4
3 2
zinc nitrate (white gelatinous ppt.)
Pb(NO ) (aq) + 2NH OH(aq) o 2NH NO (aq) + Pb(OH) (s) Insoluble
4
2
3
3 2
lead nitrate 4 ammonium nitrate lead hydroxide (white)
With copper sulphate. When ammonium hydroxide is added to a
solution of copper sulphate, a bluish white precipitate is formed. On
further addition of ammonium hydroxide, this precipitate dissolves
to give a deep blue-coloured solution due to the formation of the
complex tetraammine copper sulphate.
CuSO (aq) + 2NH OH(aq) o Cu(OH) p + (NH ) SO (aq)
4
4
2
4
4 2
copper sulphate (bluish-white ppt.)
Cu(OH )(s) + (NH ) SO + 2NH OH(aq) o [Cu(NH ) ]SO 4 + 4H O
3 4
4 2
2
4
2
4
copper(III) tetraamminecopper(II) sulphate
hydroxide (deep blue)
With silver chloride. Silver chloride is insoluble in water, but dissolves
in ammonium hydroxide forming a complex diamminesilver(I)
chloride.
AgCl(s) + 2NH OH(aq) o [Ag(NH ) ]Cl + 2H O
3 2
2
4
silver chloride diammine silver(I) chloride
(insoluble) (soluble)
Catalytic oxidation of ammonia. When a mixture of ammonia and
CKT QZ[IGP KU RCUUGF QXGT JGCVGF u% RNCVKPWO QT RNCVKPWO
rhodium catalyst, it gets oxidised to nitric oxide (NO).
Pt–Rh
Reaction: 4NH (g) + 5O (g) o 4NO(g) + 6H O(g)
3
2
2
ammonia u% nitric oxide
Reactants. Ammonia (NH ), Oxygen (O ) or Air.
3
2
Products. Nitric oxide (NO), Nitrogen dioxide (NO ), Water
2
Procedure. Dry ammonia gas and oxygen gas are fed into
a combustion tube containing hot platinum (catalyst). Hot
Fig. 9.7 Catalytic oxidation of ammonia resulting in the platinum glows emitting reddish light.
formation of nitric oxide
