CHEMISTRY PRACTICAL NOTES - SALT ANALYSIS
| Noted the colour of the salt
| BluePale greenGreenPale pinkColourless
| May be Cu2+May be Fe2+May be Ni2+, Cu2+May be Mn2+Absence of Cu2+, Fe2+, Ni2+, Cu2+, Mn2+
| Noted the physical state of the salt
| May be CO32-May be Cl-, Br-, SO42-, NO3-
| Action of heat:The given salt is heated in a dry test tube.
| (i)Reddish brown vapours(ii)Crackling sound(iii)Yellow when salt and white when cold(iv)Colourless gas giving pungent smelling gas(v) No characteristic change
| Presence of NO3-, NO2-Presence of nitrates of lead and bariumPresence of Zn2+Presence of NH4+Absence of nitrate, nitrite, zinc and ammonium ions
| Solubility: a) In water b) In dil. HCl
| SolubleSoluble in dil. HCl but insoluble in water
| Water soluble saltsPresence of CO32-
| Flame test:A paste of the salt was made with few drops of con. HCl and was introduced into the non-luminous flame.
| (i)Brick red colour is imparted to the flame(ii) Crimson red(iii) Apple green(iv) Bluish green(v)No characteristic colour is imparted to the flame
| Presence of Ca2+Presence of Sr2+Presence of Ba2+Presence of Cu2+Absence of Ca2+, Sr2+, Ba2+, Cu2+
| Ash test:To the salt added cobalt nitrate solution and dilute nitric acid. A filter paper dipped in this mixture was burnt.
| (i) Green ash(ii) Blue ash(iii) Pink ash 2Co(NO3)2 2 CoO + 4NO2 + O2 ZnO + CoO CoZnO2 MgO + CuO MgCoO2 Al2O3 + CoO Co(Al2O3)3(iv) No characteristic coloured ash
| Presence of Zn2+Presence of Al3+Presence of Mg2+Absence of Zn2+, Al3+, Mg2+
| Dry tests for anion:To a pinch of the salt , dil HCl was added and heated.
| (i)Brisk effervescence, colourless gas evolved turning lime water milkyCO32- + 2H+ CO2 + H2OCO2 + Ca(OH)2 CaCO3 + H2O(ii)Colourless gas with rotten egg smelling turning lead acetate paper black is evolved. S2- + 2H+ H2SPb(CH3COO)2+H2S PbS + 2CH3COOH(iii) No characteristic change
| Presence of CO32-Presence of S2-Absence of CO32- and S2-
| To a portion of the salt, con. H2SO4 was added and warmed.
| (i)Pungent smelling gas giving dense white fumes with a glass rod dipped in ammonia solution.Cl- + H2SO4 HClHCl + NH3 NH4Cl(ii)Orange brown vapours of bromine turning moist starch paper yellow X- + H2SO4 X2 + HSO4-(iii) Violet vapours of I2 turning starch paper blue(iv) Reddish brown vapours of NO2(v) No characteristic coloured gas is evolved
| Presence of Cl-Presence of Br-Presence of I-Presence of NO3-Absence of NO3-, X-
| Manganese dioxide test:A portion of the salt is heated with con. H2SO4 and Manganese dioxide.
| (i) Greenish yellow gas is evolved(ii) Orange brown gas(iii) Dense violet fumes(iv) No characteristic coloured gas is evolved.NaX + MnO2+ H2SO4 NaHSO4+MnSO4+ H2O + X2
| Presence of Cl-Presence of Br-Presence of I-Absence of X-
| Copper turnings test:A portion of the salt is heated with copper turnings and con. H2SO4
| (i) Reddish brown vapours of NO2 is evolved(ii) The solution turns green on coolingNO3- + H2SO4 HSO4- + HNO34HNO3 + Cu Cu(NO3)2 + 2H2O+2NO2
| Presence of NO3-
| Chromyl chloride test:The salt is heated with K2Cr2O7 and con. H2SO4. 4NaCl + K2Cr2O7 + 6H2SO4 2 CrO2Cl2 + 4H2O H2CrO4 + CH3COO)2Pb
| Evolution of red vapours of CrO2Cl2 which turns lead acetate paper yellow NaHSO4 + 2KHSO4 + 2CrO2Cl2 + 3H2O 2H2CrO4 + 4HCl PbCrO4 + 2CH3COOH
| Presence of Cl-
PREPARATION OF SODIUM CARBONATE EXTRACT:
It is prepared in the case of insoluble salts to convert the anion into soluble salt. The salt was mixed with twice the amount of sodium...
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