qualitative_analysis_

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                            Qualitative analysis of anions
                 2-
Carbonates (CO3 )
     experiment                     observation                        inference
 1* salt + dil H2SO4                brisk effervescence with          presence of carbonate is
                                    evolution of colourless           identified
                                    odourless gas which turns
                                    lime water milky
 2   salt solution + MgSO4 solution white precipitate                 presence of carbonate is
                                                                      confirmed

Acetates ( CH3COO- )
     experiment                        observation                     inference
 1* salt + dil H2SO4                   smell of vinegar               presence of acetate is
     + rubbing on a watch glass                                       identified
 2 salt solution + neutral FeCl3       blood red colour               presence of acetate is
     solution                                                         confirmed


Chlorides ( Cl-)
     experiment                        observation                     inference
 1* salt + conc H2SO4                  evolution of colourless gas    presence of chloride is
     + heat                            which gives dense white        identified
                                       fumeswhen glass rod dipped
                                       in NH4Cl is shown to the
                                       mouth of the test tube
 2   salt solution + dil HNO3+boil     white precipitate soluble in   presence of chloride is
     +AgNO3 solution                   excess of NH4OH                confirmed


Bromides ( Br -)
    experiment                         observation                     inference
 1* salt + conc H2SO4                  evolution of reddish brown     presence of bromide is
    + heat                             vapours                        identified

 2   salt solution + dil HNO3 + boil   light yellow precipitate       presence of bromide is
     + AgNO3 solution                  partially soluble in excess    confirmed
                                       NH4OH
                                        2


Iodides ( I -)
      experiment                     observation                      inference
 1* salt + conc H2SO4                evolution of violet vapours     presence of iodide is
      + heat                                                         identified
 2 salt solution + dil HNO3+boil     dark yellow precipitate         presence of iodide is
      +AgNO3 solution                which is insoluble in excess    confirmed
                                     NH4OH

Nitrates ( NO3 - )
      experiment                     observation                      inference
 1* salt + conc H2SO4                evolution of reddish brown      presence of nitrate is
      + Cu powder + heat             vapours                         identified

 2   salt +freshly prepared FeSO4 + brown ring is formed at the      presence of nitrate is
     conc H2SO4 along the sides of junction of two liquids           confirmed
     the test tube


Sulphates ( SO42-)
     experiment                    observation                     inference
 1* salt + dil HCl+ BaCl2 solution White precipitate insoluble in presence of sulphate is
                                   conc HCl                       identified

 2   salt solution + acetic acid+    white precipitate soluble in    presence of sulphate is
     + lead acetate                  ammonium acetate                confirmed


Phosphates ( PO43-)
     experiment                      observation                      inference
 1* salt + concHNO3 + solid          canary yellow precipitate       presence of phosphate
     ammonium molybdate and                                          is identified
     keep for some time
 2 salt + dilHCl + boil              white crystalline precipitate   presence of phosphate
     + magnesia mixture                                              is confirmed


          * represents identification tests for getting anions, you have to do the
           identification tests in the same order. Carbonates-acetate-
           (chloride,bromide,iodide)-nitrate-sulphate-phosphate
                                        3




                             Identification tests for anions

     experiment                      observation                     inference
1*   salt + dil H2SO4                a)brisk effervescence with     presence of carbonate is
                                     evolution of colourless        identified
                                     odourless gas which turns
                                     lime water milky
                                     b) no change                   absence of carbonate
2    salt + dil H2SO4                a)smell of vinegar             presence of acetate is
     + rubbing on a watch glass                                     identified
                                     b)no change                    absence of acetate
3    salt + conc H2SO4               a) evolution of colourless gas a)presence of chloride is
     + heat                            which gives dense white      identified
                                       fumes when glass rod
                                       dipped in NH4Cl is shown
                                       to the mouth of the test tube
                                     b) evolution of reddish brown b)presence of bromide
                                        vapours
                                     c) evolution of violet vapours c) presence of iodide
                                     d) no change                    d) absence of chloride,
                                                                     bromide and iodide
4    salt + conc H2SO4               a)evolution of reddish brown a)presence of nitrate is
     + Cu powder or paper ball +     vapours                         identified
        heat
                                     b)no change                    b)absence of nitrate

5    salt + dil HCl+ BaCl2 solution a)White precipitate insoluble   a)presence of sulphate
                                    in conc HCl                     is identified
                                    b)no change                     b)absence of sulphate

6    salt + concHNO3 + solid         canary yellow precipitate      presence of phosphate
     ammonium molybdate and                                         is identified
     keep for some time
                                               4


                                  Analysis of cations

Preliminary analysis
1.Observation of colour

      experiment                         observation             inference
 1    Colour of the salt                    a) blue colour       presence of copper Cu2+ ( Gr-II)
                                            b) brown colour      presence of Fe3+ (Gr-III)
                                            c) green colour      presence of nickel( Ni2+)-(Gr-IV)



2. Ash test

      experiment                           observation          inference
 1    salt +conc HNO3 + cobalt                a) blue ash       presence of Al3+ ( Gr-III)
      nitrate soln + boil,dip a filter        b) green ash      presence of Zn2+ (Gr-IV)
      paper and burn it in to ashes           c) pink/flesh ash presence of Mg2+(Gr-VI)



3.Flame test

      experiment                           observation           inference
 1    salt + conc HCl, make paste             a) brick red       presence of Ca2+ ( Gr-V)
      and show some portion in to                coloured
      the flame with wooden stick                flame           presence of Ba2+(Gr-V)
                                              b) pale green
                                                 coloured
                                                 flame


          by doing above tests we can identify group III,IV,V and VI cations.
          the remaining are group I and group II that can be identified by normal method
           (given below)
                                        5




                     Systematic analysis of cations
*salt solution is prepared by dissolving salt in required amount of water


            Experiment                  Observation             Inference
1   Salt soln + Na2CO3 soln      No precipitate       presence of group Zero ( NH4+)
2   Salt soln + dil HCl          White precipitate    presence of group I (Pb2+)
3   Salt soln + dil HCl + pass   Black precipitate    presence of group II (Cu2+)
    H2S gas
4   Salt soln +solid NH4Cl +   a) Gelatinous white    Presence of group III ( Al3+)
    excess NH4OH                  precipitate
                               b) Reddish brown       Presence of group III ( Fe3+)
                                  precipitate
5   Salt soln +solid NH4Cl +   a) Black precipitate   Presence of group IV( Ni2+)
    excess NH4OH + pass H2S    b) Dirty white         Presence of group IV ( Zn2+ )
    gas                           precipitate
6   Salt soln +solid NH4Cl + White precipitate        Presence of group V
    excess NH4OH +                                    ( Ba2+ or Ca2+ )
    ammonium carbonate
7   Salt soln +solid NH4Cl + White precipitate        Presence of group VI
    excess NH4OH +                                          (Mg2+)
    disodium hydrogen
    phosphate (Na2H2PO4 )
                                         6




                            Confirmatory tests for cations

             Experiment                     Observation                   Inference
1   Salt soln +                    reddish brown precipitate    presence of NH4+ is
     Nessler’s reagent                                          confirmed
2   Salt soln + KI + heat + cool yellow precipitate which       presence of lead ( Pb2+) is
    suddently in ice cold water dissolves on heating and        conformed
                                   appears as golden spangles
                                   on cooling
3   Salt son + excess NH4OH        blue precipitate which       presence of (Cu2+) is
                                   dissolves in excess NH4OH    confirmed
                                   to form deep blue coloured
                                   soln
4   salt +conc HNO3 + cobalt           blue ash                 presence of Al3+ is
    nitrate soln + boil,dip a                                   confirmed
    filter paper and burn it in to
    ashes
5   Salt soln + Pot. ferro         Prussian blue colour         presence of Fe3+ is
    cyanide                                                      confirmed
6   salt +conc HNO3 + cobalt           green ash                presence of Zn 2+ is
    nitrate soln + boil,dip a                                   confirmed
    filter paper and burn it in to
    ashes
7   salt + conc HCl, make              c) brick red coloured    presence of Ca2+ is
    paste                                 flame                 confirmed
    and show some portion in
    to the flame with wooden           d) pale green coloured   presence of Ba2+ is
    stick                                 flame                 confirmed

8   salt +conc HNO3 + cobalt         pink ash                   presence of Mg2+ is
    nitrate soln + boil,dip a                                   confirmed
    filter paper and burn it in to
    ashes

				
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posted:8/18/2012
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