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               Insoluble Salts



                                                                                              Insoluble Salts

        (a) all carbonates except ammonium carbonate [(NH4)2CO3], sodium carbonate (Na2CO3) and potassium carbonate (K2CO3)

        (b) all oxides except calsium oxide (CaO), barium oxide (BaO), sodium oxide (Na2O) and potassium oxide (K2O)

        (c) all hydroxides except ammonium hydroxide (NH4OH), sodium hydroxide (NaOH), potassium hydroxide (KOH) and barium     

             hydroxide [Ba(OH)2]

        (c) silver chloride (AgCl), lead (II) chloride (PbCl2), and mercury chloride (HgCl2)

             * Lead (II) chloride dissolves in hot water but not in cold water

          (d) barium sulphate (BaSO4), lead (II) sulphate (PbSO4), and calsium sulphate (CaSO4)








                                                                         Preparation of insoluble salts

                                                        +          Text Box: Soluble aqueuos solution that contain the anion (nonmetal ion)
                                          +Text Box: Soluble aqueuos solution that contain the anion (nonmetal ion)



         (a) Pb(NO3)2 (aq)              +                    H2SO4 (aq)                                        PbSO4 (s)              +       2HNO3(aq)                                lead (II) nitrate                                              sulfuric acid                                               lead (II) sulphate                          nitric acid

         (b) CaCl2       (aq)              +                    Na2CO3 (aq)                                      PbSO4 (s)              +        2NaCl (aq)                                calsium chloride                                            sodium carbonate                                          lead (II) sulphate                       sodium chloride      






                                                                                 Methods of preparing insoluble salts

Text Box: Precipitation of salt by double decomposition reaction
Text Box: Dry Crystals





                                                                                                                              -Filtration (use residue)








                                                                        Physical characteristics of salt crystals

        (a) Similar geometric shapes, for example cuboid, tetragonal, monoclinic, and hexagonal.

        (b) They have even surfaces, straight edges and sharp tips.

        (c) The angles between two corresponding surfaces are fixed and equal.

        (a) whether the salt is soluble or not in water

        (b) if soluble, whether it is a sodium, potassium or ammonium salt or not.