READY REFERENCE CHART.pdf
- 1. READY REFERENCE CHART FOR QUALITATIVE ANALYSIS OF BASIC RADICALS Make the solution of the given mixture in distilled water, in dil. HCl or conc. HCl cold or hot. Label it original solution (O.S.). To the O.S., add dil. HCl. If group I is absent, pass H₂S gas through O.S. for suf icient time after acidi ication with dil. HCl & Filter. White ppt. (Pb²⁺) Con irmation of Pb²⁺ Boil white ppt. with distilled water and divide the solution into two parts : (i) Add KI solution to one part of above solution. con irms Pb²⁺. Yellow ppt. (ii) Add K₂CrO₄ solution to the second part of the above solution. Yellow con irms Pb²⁺ ppt. Ppt. -Group II Black ppt. - (Pb²⁺, Cu²⁺) Yellow ppt. - (As³⁺) Dissolve, the black ppt. in minimum quan- tity of 50% HNO₃₊To one part of the above solution add dil. H₂SO₄ and alcohol. If a white ppt. is formed Pb²⁺ is indicated. If no white ppt. is formed, add excess NH₄OH to the second part of solution - Blue coloured solution indicates Cu²⁺ Con irmation of Cu²⁺ (i) Add excess of NH₄OH solution to original solution. Deep blue solution. (ii) Acidify the above deep blue solution with dil. acetic acid. Add Pot. ferrocyanide solution. Chocolate brown ppt. con irms Cu²⁺ Con irmation of Pb²⁺ (i) To the O.S. add KI Pot. iodide test. solution Yellow ppt. (ii) To the O.S. add Pot. chromate test. K₂CrO₄ Yellow ppt. If the ppt. obtained is yellow in colour - As³⁺ is indicated. Con irmation of As³⁺ (i) Yellow ppt. Amm. molybdate test. + conc. HNO₃ + Amm. molybdate solution - Yellow ppt. Magnesia mixture test. (ii) To the O.S. add magnesia mixture - White ppt. If group II is absent, add solid NH₄Cl, O.5 ml conc. HNO₃ to the O.S. Boil and cool & add NH₄OH till it smells of ammonia. If a ppt. is formed, group III is present. Reddish brown ppt. - (Fe³⁺) White ppt. - (Al³⁺) Con irmation of (Fe³⁺) Dissolve the brown ppt. in dil. HCl and divide the solution into two parts. (i) To one part of solution add pot. ferrocyanide solution. A prussion blue colour ppt. or (iii) To second part of solution add pot. sulphocyanide solution - A blood red colouration. Con irmation of Al³⁺ (i) Perform charcoal cavity - cobalt nitrate test with white ppt. Blue mass. (ii) White ppt. + dil. HCl + a Lake test. few drops of blue litmus solution + NH₄OH Solution in excess. A blue ppt., suspended in a colourless medium (called a lake). If group III is absent, through a part of the solution obtained in Group III pass H₂S gas. if a ppt. is obtained group IV is present. White ppt - (Zn²⁺) Black ppt. - (Ni²⁺ and Co²⁺) Flesh coloured ppt. - (Mn²⁺) Con irmation of Zn²⁺ Dissolve a part of white ppt. in dil. HCl and divide the solution in two parts (i) To one part of solution add pot. ferrocyanide solution- Bluish white ppt. (ii) To second part of solution add NaOH White ppt. soluble in excess. solution. Con irmation of Ni²⁺ and Co²⁺ + If the ppt. obtained is black Ni²⁺or Co² is indicated. Note the colour of the salt, if the salt is greenish - Ni²⁺ is indicated and if the salt is purple Co²⁺is indicated Con irmation of Co²⁺ (i) Take O.S. and neutralise the acid by adding NH₄OH. Add a pinch of potassium nitrite and acidify with dil. acetic acid - Yellow ppt. (ii) Perform borax bead test with salt Blue bead. Con irmation of Ni²⁺ (i) Take O.S. and make alkaline by adding NH₄OH and then add a few drops of dimethyl glyoxime - Bright red ppt. (ii) Perform borax bead test with salt- Brown bead in oxidising lame and grey bead in reducing lame. Con irmation of Mn²⁺ (i) Dissolve lesh coloured ppt. in dil. HCI, boil off H₂S , add NaOH and Br₂ water - White ppt. turning grey. (ii) Perform borex bead test with group ppt - in oxidising lame and Pink bead colourless in reducing lame. If group IV is absent, to the O.S. add solid NH₄CI, NH₄OH and (NH₄)₂CO₃ Solution. White ppt. - (Ba , Sr , Ca ) ²⁺ ²⁺ ²⁺ Dissolve a part of white ppt. in dil. acetic acid & boil off CO . ₂ (i) To one part of the above solution add Con irms K₂CrO₄ solution. Yellow ppt. Ba²⁺ (ii) If Ba²⁺ is absent, then to the second part of above solution add ammonium sulphate solution. White ppt. - A con irms Sr . ²⁺ (iii) If Both Ba and Sr are absent, then ²⁺ ²⁺ to the third part of the above solution add ammonium oxlate solution. A white ppt. con irms Ca . ²⁺ Perform the lame test with a part of the salt. (i) con irmed. Light green lame-Ba²⁺ Crimson red lame- Sr (ii) con irmed. ²⁺ (iii) con irmed. Brick red lame - Ca²⁺ If group V is absent, test for Mg²⁺ (i) To the O.S. add a pinch of NH₄Cl, a few drops of NH₄OH and excess of solution - amm. phosphate White ppt.- Mg²⁺ (ii) Perform charcoal cavity cobalt nitrate test with white ppt. - A Pink mass. Test for NH₄⁺ Heat the salt and sodium hydroxide solution. If ammonia gas evolves, NH₄⁺ is present. Pass the gas through Nessler's reagent. A brownish ppt. or colouration is obtained. Note. NH₄⁺ may be tested in the beginning of analysis of basic redicals as zero group.
- 2. READY REFERENCE CHART FOR QUALITATIVE ANALYSIS OF ACID RADICALS Dil. H₂SO₄Test Treat the salt with dil. H₂SO₄ (i) CO₂gas, turns lime water milky - CO₃² 2 (ii) H₂S gas (smells like rotten eggs), turns lead acetate paper black - S 2 (iii) SO₂ gas, turns acidi ied potassium dichromate paper green - SO₃ (iv) NO₂ gas (reddish brown), turns FeSO₄solution black - NO₂ CONFIRMATORY TESTS Con irmation of CO₃² Try to dissolve the salt in water. If the salt dissolves is indicated. soluble CO - ₃² (i) To the solution add dil. HCl - evolves with brisk effervescence. CO₂ gas (ii) To the solution add MgSO₄ solution con irms soluble carbonate. - White ppt. If the salt does not dissolve in water - is indicated. insoluble carbonate To the solid salt add dil. HCl - CO₂ gas evolves with brisk effervescence - con irms insoluble carbonate. - Con irmation of S² (i) W.E. or S.E. + acetic acid + lead acetate solution - Black ppt. colouration. (ii) W.E. or S.E. + Sod. nitroprusside solution - A purple or violet - A yellow ppt. (ii) W.E. or S.E. + suspension of CdCO₃ - Con irmation of SO₃² (i) W.E. or S.E. + BaCl₂ solution - which dissolves with evolution of White ppt. SO₂ on adding dil. HCl. (ii) Salt + a few drops of acidi ied KMnO₄ - Pink colour of KMnO₄ disappears. - Con irmation of NO₂ (i) W.E. + acetic acid + FeSO₄ - Dark brown or black colour. - Blue (ii) W.E. + 2-3 drops of H₂SO₄ + KI solution + 2-3 drops of starch solution colouration. (iii) W.E. + a few drops of acidi ied KMnO₄ solution - Pink colour disappears. If no gas is evolved when the salt is treated with dilute sulphuric acid. - Absence of CO₃² , S² , SO₃² and NO₂ - - - - Conc. H₂SO₄ Test Heat a pinch of the salt with conc. H₂SO₄ - (i) HCl gas gives white ppt. (soluble in NH₄OH) with AgNO₃ - Cl - (ii) Br₂ gas turns starch paper yellow or orange - Br. . - (iii) I₂ vapours turns starch paper blue - I . - (iv) NO₂ gas (on adding a paper pellet) turns FeSO₄ solution black - NO₃ 2- (v) A colourless, odourless gas (CO₂) - C₂O₄ - (vi) Colourless vapours with vinegar smell - CH₃COO CONFIRMATORY TESTS - Con irmation of Cl (i) To the salt solution add conc. HNO₃ and AgNO₃ solution -A soluble white ppt. in NH₄OH solution. (ii) To the salt add MnO₂ and conc. H₂SO₄ and heat - Cl₂ gas evolves. (iii) Salt + K₂Cr₂O₇ solid + conc. H₂SO₄, heat - Red vapours. Pass the vapours through NaOH solution. To the yellow solution obtained add acetic acid and - lead acetate solution con irms Cl - yellow ppt. - Con irmation of Br (i) Salt solution + conc. HNO₃ + AgNO₃ solution - Pale yellow ppt. partially soluble in NH₄OH. (ii) Salt solution + dil. HCl + 1-2 ml of carbon disulphide + Chlorine water test. chlorine water, shake - Orange colour in CS₂ layer. - Con irmation of I (i) Salt solution + conc. HNO₃+ AgNO₃ solution - Yellow ppt. insoluble in NH₄OH. (ii) Salt solution + dil. HCl + 1-2 ml of CS₂+ Chlorine Chlorine water test. water, shake - violet colour in CS₂ layer. - Con irmation of CH₃COO (i) Solid salt + oxalic acid + 2-3 drops of water, rub - Oxalic acid test. Vinegar smell. (ii) Ester test. - Fruity smell. Salt + conc. H₂SO₄ + Ethyl alcohol, heat 2- Con irmation of C₂O₄ (i) Salt solution + acetic acid + CaCl₂ solution - White ppt. - Pink colour is (ii) Salt + dil. H₂SO₄, warm and add 2-3 drops of KMnO₄ solution discharged. - Con irmation of NO₃ (i) Mixture + conc. H₂SO₄+ Cu chips. Heat - Reddish brown gas. - Dark brown (ii) W.E. + FeSO₄ solution + conc. H₂SO₄ by the sides of the tube ring. If no gas is evolved when mixture is heated with conc. H₂SO₄₊ - - - - - - Absence of Cl , Br , I , NO₃ , CH₃COO and C₂O₄² If the salt does not react with dil. H₂SO₄ as well as conc. H₂SO₄ test for - - SO₄² and PO₄ ³ - Con irmation of SO₄² (i) W.E. or S.E. + dil. HCl + BaCl₂ Solution - Barium chloride test. White ppt. insoluble in dil HCl (ii) Mix the salt with Na₂CO₃. Make its paste. Fuse a little Match stick test. paste on the end of match stick. Dip the fused mass in sod. nitroprusside solution - Purple steaks. - Con irmation of PO₄³ (i) S.E. + conc. HNO₃ and boil. Now add amm. Ammonium molybdate test. molybdate sol. and heat - Yellow ppt. (ii) W.E. or neutral S.E.+ Magnesia mixture Magnesia mixture test. - White ppt.
- 3. Table : Physical Examination 1. Colour Experiment Observations Inference 2. Smell 3. Density 4. Deliquescence Blue or bluish green Greenish Light green Dark brown Pink Light pink, lesh colour or earthy colour White Ammonical smell Vinegar like smell Smell like that of rotten eggs (i) Heavy (ii) Light luffy powder Salt absorbs moisture and becomes paste like Cu²⁺or Ni²⁺ Ni²⁺ Fe ²⁺ Fe ³⁺ Co²⁺ Mn²⁺ Shows the absence of Cu²⁺, Ni²⁺, Fe²⁺, Fe ³⁺, Mn²⁺, Co²⁺ NH₄⁺ - CH₃COO - S² Salt of Pb ²⁺ or Ba²⁺ Carbonate (i) If coloured, may be Cu(NO₃)₂ , FeCl₃ (ii) If colourless, may be Zn(NO₃)₂ , chlorides of Zn²⁺, Mg²⁺ etc. Take a pinch of the salt between your ingers and rub with a drop of water
- 4. Take a small quantity of the salt in a test-tube and add 1-2 ml of dilute sulphuric acid. Identify the gas and draw inferences from Table DILUTE SULPHURIC ACID TEST Table : Dilute Sulphuric Acid Test Inference Gas Radical Observations 1. Colourless, odourless gas with brisk effervescence, turns lime water milky. 2. Colourless gas, pungent smell, turns acidi ied potassium dichromate paper or solution green. 3. Colourless gas, with smell, like that of rotten eggs, turns lead acetate paper black. 4. Reddish brown gas, punget smell, turns ferrous sulphate solution black. 5. No gas is evolved. CO₂ SO₂ H₂S NO₂ ------- - CO₃² - SO₃² - S² - NO₂ - - - CO₃² , SO₃² , S² - NO₂ absent Note : 1. Do not treat the salt with a large quantity of dilute acid. 2. Do not heat the salt with dilute acid.
- 5. This test is performed by treating small quantity of salt with conc. sulphuric acid (2-3 ml) in a test tube. Identify the gas evolved in cold and then on heating. Draw inferences from table. CONCENTRATED SULPHURIC ACID TEST Table : Conc. Sulphuric Acid Test Inference Gas Radical Observations 1. Colourless, gas with pungent smell, white fumes with aqueous ammonia (NH₄OH), white ppt. with AgNO₃ solution. 2. Reddish brown vapours with pungent smell, turns starch paper yellow. It does not turn FeSO₄ solution black. 3. Deep violet vapours with pungent smell, turns starch paper blue. A sublimate is formed on the sides of the tube. 4. Reddish brown gas with pungent smell, turns FeSO₄ solution black. 5. Colourless vapours, vinegar smell, turns blue litmus red. 6. A colourless gas which turns lime water milky and also a gas which burns with pale - bluish lame 7. No gas/vapours evolved. HCl Br₂ I₂ vapours NO₂ CH₃COOH vapours. CO₂ + CO -------- - Cl - Br - I - - - - Cl ,Br I , NO₃ , - CH₃CHOO absent - C₂O₄² - NO₃ - CH₃COO 1. Do not boil the salt with conc. sulphuric acid. On boiling the acid may decompose to give SO₂ gas. 2. Nitrates give vapours of nitric acid (colourless) when heated with conc. sulphuric acid. When a paper pellet or copper chips is added. dense brown fumes evolve. Paper pellet acts as a reducing agent and reduces nitric acid to NO₂ (Reddish brown gas.) 12.9. Note:
- 6. The following table will help the students in the choice of a suitable solvent : 12.9. QUALITATIVE ANALYSIS Solvent 1. Cold water 2. Hot water 3. Dil. HCl Salts which dissolve + + + (a) All NH₄ , Na and K salts. (b) All nitrites, nitrates and acetates. (c) Most of the sulphates except that those of Pb, Ba, Ca, Sr. (d) All chlorides except that of lead. Lead chloride, lead nitrate. All carbonates which do not dissolve in water i.e., Carbonates of Ca, Ba, Sr, Mg, Zn, Al, Cu, Ni, Mn, Fe etc. but not of Pb. The separation of cations into various groups by making use of suitable reagents (known as a group reagents) is based on the differences in chemical properties of cations. For example, if hydrochloric acid is added to a solution containing all cations, only the chlorides of lead, silver and mercury (ous) will precipitate, since all other chlorides are soluble. Thus, these cations form a group of ions which may be precipitated from solution by addition of group reagent HCl. Similarly, H₂S is a group reagent for group II. The following Table clearly shows the group reagents for different groups and the form in which cations of the particular group are precipitated out. Group Group reagent Cations Form in which cations are precipitated Group Zero No Group I Group II Group III Group IV Group V Group VI Dilute HCl H₂S in the presence of dilute HCl NH₄OH in the presence of NH₄Cl H₂S in the presence of NH₄OH (NH₄)₂CO₃ in the presence of NH₄OH No ----- Chlorides Sulphides Hydroxides Sulphides NH₄⁺ Pb ²⁺ Mg ²⁺ Pb²⁺ Cu²⁺, As ³⁺ Fe³⁺, Al ³⁺ Ni ²⁺, Mn ²⁺, Zn²⁺ Co²⁺ Ca²⁺, Ba ²⁺, Sr²⁺ Carbonates -----