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Principles Related to Practical Chemistry

Principles Related to Practical Chemistry PDF Notes, Important Questions And Synopsis

Principles Related to Practical Chemistry PDF Notes, Important Questions and Synopsis

SYNOPSIS

  • Qualitative analysis of organic compounds: Analysis involving detection of all elements present in an organic compound.
    • Detection of carbon and hydrogen by the copper oxide test
  1. Qualitative analysis (Detection of elements):
  2. Detection of nitrogen, halogen and sulphur by Lassaigne’s test

 

  • Detection of carbon and hydrogen: Carbon and hydrogen are detected by heating the compound with copper (II) oxide. Carbon present in the compound is oxidised to carbon dioxide and hydrogen to water. Carbon dioxide is tested with lime water. Carbon dioxide makes lime water milky and develops turbidity. Water is tested with anhydrous copper sulphate, which becomes blue on absorbing moisture.

    begin mathsize 12px style table attributes columnalign left end attributes row cell straight C text   end text plus text   end text 2 CuO text    end text rightwards arrow with straight capital delta on top text   end text 2 Cu text   end text plus text   end text CO subscript 2 end cell row cell 2 straight H text   end text plus text   end text CuO text   end text rightwards arrow with straight capital delta on top text   end text Cu text   end text plus text   end text straight H subscript 2 straight O end cell row cell CO subscript 2 text   end text plus text   end text Ca open parentheses OH close parentheses subscript 2 text   end text rightwards arrow with straight capital delta on top text   end text CaCO subscript 3 text   end text plus text   end text straight H subscript 2 straight O end cell row cell 5 straight H subscript 2 straight O text   end text plus text   end text stack CuSO subscript 4 with white below text   end text rightwards arrow with straight capital delta on top text   end text stack CuSO subscript 4.5 straight H subscript 2 straight O with Blue below end cell end table end style                         
  • Detection of nitrogen: The sodium fusion extract (prepared by boiling fused mass of the compound and sodium metal in distilled water) is boiled with FeSO4 (iron (II) sulphate) and then acidified with concentrated sulphuric acid. The formation of a Prussian blue colour confirms the presence of nitrogen.

    begin mathsize 12px style table attributes columnalign left end attributes row cell 6 CN to the power of minus text   end text plus text   end text Fe to the power of 2 plus end exponent text   end text rightwards arrow with blank on top text   end text open square brackets Fe open parentheses CN close parentheses subscript 6 close square brackets to the power of 4 minus end exponent end cell row cell 3 open square brackets Fe open parentheses CN close parentheses subscript 6 close square brackets to the power of 4 minus end exponent text   end text rightwards arrow with xH subscript 2 straight O on top text   end text stack Fe subscript 4 open square brackets Fe open parentheses CN close parentheses subscript 6 close square brackets subscript 3. xH subscript 2 straight O with Prussian text    end text blue below end cell end table end style

                             
  • Detection of sulphur: Two tests can be performed for the detection of sulphur.
  1. a.       On adding lead acetate to acidified sodium fusion extract, the formation of a black precipitate confirms the presence of sulphur.
    1. a.              begin mathsize 12px style straight S to the power of 2 minus straight thin space end exponent plus straight thin space Pb to the power of 2 plus end exponent straight thin space rightwards arrow with blank on top straight thin space PbS with Black below end style                                         
    2. b.      On adding sodium nitroprusside to acidified sodium fusion extract, the appearance of violet colour indicates the presence of sulphur.

      begin mathsize 12px style straight S to the power of 2 minus straight thin space end exponent plus     open square brackets Fe open parentheses CN close parentheses subscript 5 NO close square brackets to the power of 2 minus end exponent straight thin space rightwards arrow with blank on top straight thin space stack open square brackets Fe open parentheses CN close parentheses subscript 5 NOS close square brackets to the power of 4 minus end exponent with Violet below end style
  • Detection of halogens: On adding a silver nitrate solution to sodium fusion extract acidified with nitric acid, a white precipitate (soluble in ammonium hydroxide) shows the presence of chlorine, a yellowish precipitate (sparingly soluble in ammonium hydroxide) shows the presence of bromine and a yellow precipitate (insoluble in ammonium hydroxide) shows the presence of iodine.

    begin mathsize 12px style straight X to the power of minus straight thin space plus straight thin space Ag to the power of plus straight thin space rightwards arrow with blank on top straight thin space AgX thin space       open parentheses straight thin space straight X equals Cl comma straight thin space Br comma straight thin space straight I close parentheses end style 
  • Detection of phosphorus: The compound containing phosphorus is heated with an oxidising agent (sodium peroxide) which oxidises phosphorus to phosphate. The solution is boiled with nitric acid and then treated with ammonium molybdate. A yellow colouration or precipitate indicates the presence of phosphorus.

    begin mathsize 12px style table attributes columnalign left end attributes row cell text                                                           end text Na subscript 3 PO subscript 4 text   end text plus text   end text 3 HNO subscript 3 text   end text rightwards arrow with blank on top text   end text straight H subscript 3 PO subscript 4 text   end text plus text   end text 3 NaNO subscript 3 end cell row cell straight H subscript 3 PO subscript 4 text   end text plus stack text   end text 12 text   end text open parentheses NH subscript 4 close parentheses subscript 2 MoO subscript 4 with table attributes columnalign left end attributes row Ammonium row molybdate end table below text   end text plus text   end text 21 HNO subscript 3 text    end text rightwards arrow with blank on top text    end text stack open parentheses NH subscript 4 close parentheses subscript 3 PO subscript 4.12 MoO subscript 3 with table attributes columnalign left end attributes row cell text             end text Ammonium end cell row phosphomolybdate end table below text   end text plus text   end text 21 text   end text NH subscript 4 NO subscript 3 text   end text plus text   end text 12 straight H subscript 2 straight O end cell end table end style
  • Qualitative Analysis of Inorganic Compounds:
    Identification of acidic radicals (anions):

Identification of basic radicals (cations):

Group I

Group II

Group II(a)

Group II(b)

Group III

Group IV

Group V

Group VI

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