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                Soluble Salts



                                                                                         What is solubility?

       (a) to separate a salt from a mixture of salts

       (b) to prepare a salt sample





       (c) to identify cations and anions through qualitative analysis






                                                                                              Soluble Salts

        (a) all nitrates and ethanoates

        (b) all sodium, potassium and ammonium salts

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

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

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

          (e) lead halides that is lead (II) chloride (PbCl2), lead (II) iodide (PbI2), lead (II) bromide (PbBr2), only dissolve in hot










                                                                         Preparation of soluble salts

        (a) Reaction between acid and alkali/base called neutralization/titration:

             acid + alkali                  salt + water

        (b) Reaction between acid and base oxide:

             acid + oxide/hydroxide metal                  salt + water               

        (c) Reaction between acid and reactive metal:

             acid + metal                  salt + hydrogen

        (d) Reaction between acid and metal carbonate:

             acid + carbonate metal                  salt + water + carbon dioxide 












                                                                                 Methods of preparing soluble salts

1. Soluble salts of sodium, potassium and ammonium salts

Text Box: Acid + alkali
Text Box:  Saturated salt solution
Text Box: Dry Crystals
Text Box: Formation of crystals
Text Box: Dilute salt solution










                                                                                                    Filtration + Drying



        KOH (aq) + HNO3 (aq)                      KNO3 (aq) + H2O (l)

Salt solution + Excess solid

        NaOH (aq) + HCl (aq)                     NaCl(aq) + H2O (l)

        2NH3 (aq) + H2SO4 (aq)                     (NH4)2SO4 (aq)

        2NaOH (aq) + H2SO4 (aq)                     Na2SO4 (aq) + H2O (l) 

Residue: Excess solid reactant


Dry crystals
Filtrate: Dilute salt solution

2. Soluble salts that is exclude of sodium, potassium and ammonium salts



                                                                                                     + metal or oxide/hydroxide/carbonate metal in excess 














                                                    Evaporation/Boiling, Cooling, Filtration






         (a) Zn (s)    +    H2SO4 (aq)            ZnSO4 (aq)    +    H2 (g)

              (metal   +    acid             salt    +    hydrogen)

         (b) Zn0 (s)    +    H2SO4 (aq)            ZnSO4 (aq)    +    H2O(l)

              (oxide metal   +    acid             salt    +    water)

         (c) Zn(OH)2 (s)    +    H2SO4 (aq)            ZnSO4 (aq)    +    2H2O(l)

              (hydroxide metal   +    acid             salt    +    water)

         (d) ZnCO3 (s)    +    H2SO4 (aq)            ZnSO4 (aq)    +    H2O(l)    +    CO2 (g) 

              (carbonate metal   +    acid              salt    +    water    +    carbon dioxide)


















Dilute acid