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PRACTICAL CHEMISTRY, , , , , , , , , , , , , , , , * Practical Inorganic Chemistry : Chemical Q_ Some tests like dry heating test, flame test, borax, principles involved in the qualitative salt bead test, charcoal cavity test, cobalt nitrate test, analysis, chemistry involved in the preparation give preliminary idea of the radicals present in, of the inorganic compounds. the salt., , * Practical Organic Chemistry : Detection of ., extra elements in organic compounds, detection Dry Heating Test, of functional groups in organic compounds, Observation | Radicals, chemistry involved in the preparation of the lear ear et ac, organic compounds. Colourless gas evolved —§CO3 , S03 ,S", Cl, , * Practical Physical Chemistry : Chemistry Brown gas evolved | Br, NO3, involved in the titrimetric exercises, chemical Violet gas evolved iD, principles involved in the physical chemistry Crackling sound 'Pb(NOs)z, Ba(NO3)>, experiments. a Tae, , Brown residue (Cur, Q The qualitative salt analysis deals with the Flame Test, identification of acidic radicals (anions) and Q_ Salt with 1 or 2 drops of conc. HCl is introduced, basic radicals (cations) in an inorganic salt or in a in the non-luminous (oxidising part) flame of, , mixture of salts., , Q_ Im the salt, A,B,, A is positively charged ion and, Bis negatively charged ion., , the Bunsen burner using platinum wire. Some, basic radicals impart characteristic colour to the, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , flame., A,B, fanaa = anne, y ae Y Colour of flame Radicals, Als Bie Golden yellow Na*, Cation Anion «$$;, (Basic radical) (Acidic radical) Lilac Kt, Q_ Itinvolves preliminary tests and wet tests. Brick red Ca2*, 2+, Preliminary Tests Apple green Ba, Q_Itinvolves physical examination of salt like their Crimson red Sr, characteristic colour and odour. Greenish blue Cu*, Test Observation Radicals, a, Colour | White NHi, Pb Al, Botax Béad-Test, Zn**, Ba**, Ca*, . ., os os jorax is heated on a loop o} wire, colourless, si2*, Mg” Q B heated loop of Pt lourl, Blue cu" glassy bead of sodium metaborate and boric, Geen, Ni Co anhydride is formed., A, Light green Fe NapByO710H,O —*+> Na3ByO7 >, Brown Fe* 2NaBO) + B03, pe US, Pink Co** Glassy bead, Light pink Mn** Q Coloured salts are then heated on the glassy bead,, (Flesh colour) coloured metaborate is formed in the oxidising, Odour §Ammoniacal smell NH? flame., Smell of vinegar CuSO, +B,0;—> Cu(BO2), + SO, Smell of rotten eggs Copper metaborate, , , , , , , , , , (Blue)

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In reducing flame we have, , 2Cu(BO )2 + C —> 2CuBO + B2O3 + CO, 2Cu(BO,)2 + 2C —> 2Cu + 2B,03 +2CO, , Hence different colours appear in different, flames., , Colour in, , , , Metal Oxidising flame, , Hot | Cold Hot Cold, Copper Green |Blue, , Reducing flame, , , , , , , , Colourless |Brown red, , , , , , , , , , , , , , , , , , Brown |Pale Bottle Bottle, ron, , yellow lyellow green green, Chromium | Yellow |Green |Green Green, Cobalt Blue [Blue Blue Blue, Manganese | Violet zeny Colourless |Colourless, Nickel Brown |Brown Grey Grey, , , , Charcoal Cavity Test (Reduction test), , Q_ Salt is heated with fusion mixture (NazCO3 and, K2CO;) in a charcoal cavity in reducing flame to, form metallic oxides which are left as coloured, residues. The colour of the residue being, , characteristic of the basic radical present., Cobalt nitrate Test, , Q_sIf the residue in charcoal cavity test is white,, moisten it with a drop of cobalt nitrate and, on heating in an oxidising flame, colour of the, , residue will change., , Q_ Cobalt oxide, formed as a result of decomposition, of cobalt nitrate, combines with metallic oxides, to form coloured compounds, which are, , characteristic of basic radicals,, , , , Key Points, , Q > Some salts change colour on heating ¢.g.,, , CuSO4-5H,0 —*> White, Blue, , CoCl, —*> Blue, , Pink, , Ni > Yellow, Green, , Q = Cobalt nitrate test should be performed, , with 2-3 drops of cobalt nitrate solution, otherwise black cobalt oxide is formed, which will mask the colour of the residue., , , , , , , , Wet Test, , Qa, , a, , Identification of acidic radicals: Most of the salts, , liberate gas on treating with dilute hydrochloric, , acid or dilute sulphuric acid and concentrated, , sulphuric acid., , Some salts do not respond to any of these acids., , O Depending on this behaviour, acidic radicals, are divided into three groups:, , - Group I: This group consists of radicals, which are detected by dilute H SO,, or dilute HCl. These are (i) carbonate,, (ii) sulphite, (iii) sulphide, (iv) nitrite and, (v) acetate., , - Group II : This group consists of radicals, which are detected by concentrated, H)SOj,. These are (i) chloride, (ii) bromide,, (iii) iodide, (iv) nitrate and (v) oxalate., , — Group III: The radicals which do not give, any characteristic gas with dilute and, concentrated H2SO4. These are, (i) sulphate, (ii) phosphate, (iii) borate, and (iv) fluoride.