Senior Class 11 Chemistry Salt Analysis 2020-21 PDF

INDIAN SCHOOL MUSCAT SENIOR SECTION DEPARTMENT OF CHEMISTRY CLASS XI-LAB SHEET QUALITATIVE ANALYSIS OF INORGANIC SALT Experiment Number. ------------...

INDIAN SCHOOL MUSCAT SENIOR SECTION DEPARTMENT OF CHEMISTRY CLASS XI-LAB SHEET QUALITATIVE ANALYSIS OF INORGANIC SALT Experiment Number. ------------ Date: -------------- Aim: To identify the anion and cation present in the given salt systematically. PRELIMINARY EXAMINATION OF SAMPLE No: ………………. The sample is: Presence of: Blue Cu2+ ions Green Cu2+ or Ni2+ ions Dark 1 Colour of the sample is noted yellow/Brown Fe3+ or Mn(NO3)2 Flesh or light pink Mn2+ ions Yellowish brown NH4I salt Absence of transition metal Colourless / White cations. Livid Blue Presence of Pb2+ ion 2 FLAME TEST: A thick paste of the flame sample is prepared in con. HCl and is Green-edged Presence of Cu2+ ions. shown to the non-luminous part of a blue flame Bunsen flame with the help of a glass Crimson flame Presence of Sr2+ ions rod. Pale green flame Presence of Ba2+ ions Brick red flame Presence of Ca2+ ion ANALYSIS OF ANIONS 3 A little of the sample is Colourless, odourless gas Presence of CO32— ion treated with dil. HCl acid (CO2) is evolved with Note: Do the following test only if effervescence. effervescence is seen in this test. 4 A little of the sample is White fuming, pungent smelling gas Presence of Cl— ion treated with con. H2SO4. (HCl) produces dense white fumes when mouth of NH4OH bottle is shown near the mouth of the test tube. Note: Warm/Heat if necessary Note: Difference in heating plays an important role in this Reddish brown gas (NO2) on boiling the Presence of NO3— ion test. Warming = Heat for 5 - 10 mixture with copper turnings. is confirmed. seconds Confirmatory Tests for Carbonate(CO32—) ion. Pass the CO2 gas through clear limewater. Lime water turns milky CO32— ion is confirmed Confirmatory Tests for Chloride (Cl—) ion. 2020-21 Page 1 of 6  INDIAN SCHOOL MUSCAT SENIOR SECTION DEPARTMENT OF CHEMISTRY CLASS XI-LAB SHEET An aqueous solution of the sample is Thick curd like white (AgCl) treated with dil. HNO3 followed by precipitate dissolves in excess Presence of Cl— ion. AgNO3 solution. of NH4OH solution. Confirmatory Test for Nitrate (NO3—) ion. Treat an aqueous solution of the sample with dil. H2SO4, add freshly A thin dark brown ring prepared FeSO4 solution and agitate {[Fe(H2O)5NO]}forms at the junction Presence of NO3— the mixture well. Now add con. between the reaction mixture and ion is confirmed. H2SO4 to the mixture drop wise con.H2SO4. along the inside wall of the test tube. Note:  Place the test tube containing the reaction mixture in beaker containing ~50 ml tap water and then only add con.H2SO4 to avoid temperature build up due to exothermic nature of the reaction.  Mixing ratio: 1 ml of sample solution + 1ml dil.H2SO4 + 2 ml FeSO4 (aq) and then add 1 ml of con. Sulphuric acid drop by drop.  If precipitation takes during this test, add more dil.H2SO4 and then remove the precipitate by centrifugation. Confirmatory Test for Sulphate (SO42—) ion. An aqueous solution of the sample is acidified A white precipitate (BaSO4) Presence of with dil.HCl followed by the addition of BaCl2 formed, which is insoluble in SO42 – ion solution. con.HCl A white precipitate (PbSO4) An aqueous solution of the sample is acidified formed, which is soluble in SO42— ion is with dilute acetic acid followed by the addition Ammonium acetate [CH3 confirmed. of lead acetate [(CH3COO)2 Pb] solution. COONH4] solution. ANALYSIS OF CATIONS Confirmatory Tests For NH4+ ion Smell of ammonia (NH3), Agitate a pinch of the solid salt sample with which produces dense white NH4+ ion NaOH solution and note its smell. fumes when Con. HCl is confirmed. (Note: Release the gas near your nose) shown near the mouth of the test tube. The solid salt sample is treated with NaOH A brown precipitate is NH4+ ion solution followed by Nessler’s reagent. formed. confirmed. Note: Do not shake the mixture. (NH2.HgO.HgI) INTER-GROUP SEPARATION OF CATIONS A true solution of the salt is prepared in distilled water. Note:  How to prepare? - Start with a pinch of sample + 4ml of solvent. If it dissolves completely, then gradually increase the concentration by dissolving more salt.  If the sample is insoluble in water; try dissolving it in dil.HCl or dil.HNO3 2020-21 Page 2 of 6  INDIAN SCHOOL MUSCAT SENIOR SECTION DEPARTMENT OF CHEMISTRY CLASS XI-LAB SHEET About 1 ml. of the sample solution is treated with dil. White precipitate of PbCl2 Presence of group – I cations HCl Black precipitate of Copper Through the above solution sulphide (CuS) Presence of group – II cations H2S gas is passed. Note:  H2S WORK: Dirty H2S gas delivery tube & its washing water can cause contamination of your work. Students should ensure that they are neat and clean before use.  Reject any black precipitate obtained if the sample is not blue or green in colour To about 2ml. (If the sample is insoluble Gelatinous white in water; try dissolving it in dil.HCl or precipitate of Aluminium dil.HNO3) of the salt solution 2 ml of hydroxide {Al(OH)3} saturated NH4Cl solution is added. Shake Presence of group – III the mixture well and then add 7ml of cations Brown precipitate Ferric NH4OH solution and agitate. hydroxide {Fe(OH)3} Note: This solution may be called group-III solution Dirty white precipitate of Zinc sulphide Through 2 ml of the of the (ZnS) above solution (group – Buff precipitate of Manganese sulphide Presence of group – IV III solution) H2S gas is (MnS) cations passed Black precipitate of Nickel sulphide (NiS) Note: Reject any black precipitate obtained if the sample is not green in colour White precipitate of Barium To 2ml of the group – III solution carbonate (BaCO3) Strontium Presence of group – (NH4)2CO3 (Little excess) solution is carbonate (SrCO3) or Calcium V cations added carbonate (CaCO3) Confirmatory test for Magnesium (Mg ) ion 2+ To 2ml of the group –III solution Di- sodium hydrogen phosphate is added. White crystalline precipitate of Presence of Mg2+ ion (Note: Scratch the sides of the test tube Magnesium phosphate confirmed with a glass rod if necessary) 2 Drops of salt solution are treated with Presence of Mg2+ ion 3 drops of Magneson reagent and 3 Blue precipitate / solution confirmed drops of NaOH solution CONFIRMATORY TEST FOR CATIONS ANALYSIS OF GROUP – I CATION Confirmatory Tests For Lead (Pb2+) Ion To one portion of the sample solution add few Yellow precipitate of Presence of Pb2+ ion drops of Potassium chromate (K2CrO4) solution. Lead chromate confirmed 2020-21 Page 3 of 6  INDIAN SCHOOL MUSCAT SENIOR SECTION DEPARTMENT OF CHEMISTRY CLASS XI-LAB SHEET (PbCrO4) To another portion of the sample solution add few Yellow precipitate of Presence of Pb2+ ion drops of Potassium iodide (KI) solution. Lead iodide (PbI2) confirmed ANALYSIS OF GROUP – II CATIONS Confirmatory Tests For Copper (Cu2+) Ion To one portion of the sample solution Deep blue solution, Presence of Cu2+ ion add excess of NH4OH solution [Cu(NH3)4](OH)2 confirmed Treat one portion of the above deep blue solution Presence of Chocolate coloured with dil. Acetic acid followed by few drops of Cu2+ ion precipitate Cu2[Fe(CN)6] K4[Fe(CN)6] (Potassium Ferro cyanide) solution confirmed ANALYSIS OF GROUP – III CATIONS Confirmatory Tests For Aluminium (Al3+) Ion White precipitate, To one portion of the sample solution NaOH Presence of Al3+ Al(OH)3, dissolves in solution is added drop by drop. ion confirmed excess of NaOH Another portion of the sample solution is acidified with dil.HCl followed by the addition of A floating blue precipitate blue litmus solution. Shake the mixture well to Presence of Al3+ is formed (It is called the get a pink coloured solution. To this solution ion confirmed “Floating blue lake) NH4OH solution is added drop wise without shaking. ANALYSIS OF GROUP – III CATIONS. Confirmatory Tests for Ferric (Fe3+) Ion To one part of the diluted salt solution A Prussian blue Fe3+ ion K4[Fe(CN)6] (Potassium ferrocyanide) solution is colouration Fe4[Fe(CN)6]3 confirmed. added. To 2nd part of the diluted salt solution Potassium A blood red colouration Fe3+ ion thiocyanate (KCNS) solution is added. Fe(CNS)3 confirmed. ANALYSIS OF GROUP – IV CATIONS. Confirmatory Tests for Zinc (Zn2+) Ion White precipitate To one portion of the sample solution NaOH Zn2+ ion {Zn(OH)2} dissolves in solution is added drop wise without shaking. confirmed. excess of NaOH(aq) nd To 2 part of the sample solution K4[Fe(CN)6] Greenish/bluish white Zn2+ ion (Potassium Ferro cyanide) solution is added. [Zn2[Fe(CN)6] precipitate. confirmed. ANALYSIS OF GROUP – IV CATIONS. Confirmatory Tests for Manganese (Mn2+) Ion. A white precipitate To one portion of the sample solution add NaOH Mn2+ ion {Mn(OH)2} formed turns solution drop wise without shaking. confirmed. to brown (MnO2) ¼ spatula of solid sample is treated with ½ ml of A purple colour formed Mn2+ ion con.HNO3 followed by the addition of 1 ml of changes to brown on confirmed. 2020-21 Page 4 of 6  INDIAN SCHOOL MUSCAT SENIOR SECTION DEPARTMENT OF CHEMISTRY CLASS XI-LAB SHEET Sodium bismuthate solution#. standing. Note: Add water to get a colourless solution if needed ANALYSIS OF GROUP – IV CATIONS. Confirmatory Tests for Nickel (Ni2+) Ion. (Note: All salts containing Ni are Greenish in colour) To one portion of the sample solution add 10 drops of A scarlet red Ni2+ ion Dimethyl glyoxime reagent followed by excess of NH4OH precipitate. confirmed solution. To the 2nd portion of the sample solution add Br2 water A black Ni2+ ion solution followed by NaOH solution, boil and then keep precipitate. confirmed. aside. ANALYSIS OF GROUP V CATIONS Confirmatory Tests for Barium (Ba2+) ion A yellow To one portion of the sample solution add a few drops of Ba2+ ion (BaCrO4) Potassium chromate (K2CrO4) solution. confirmed. “precipitate”. To another portion of the sample solution add a few drops of Dil.H2SO4 acid. Note: A white (BaSO4) Ba2+ ion  Do this test only if the K2CrO4 test is positive precipitate. confirmed.  Do this test only as the 2 confirmatory test for nd Ba2+. ANALYSIS OF GROUP V CATIONS Confirmatory Tests for Strontium (Sr2+) ion Scanty white A portion of the sample solution is treated with acetic Sr2+ ion (SrSO4) acid followed by ammonium sulphate solution confirmed. precipitate A thick paste of the sample is prepared in con. HCl and Crimson coloured Sr2+ ion is shown to the non-luminous part of a Bunsen flame flame confirmed. with the help of a glass rod. ANALYSIS OF GROUP V CATIONS Confirmatory Tests Calcium (Ca2+) ion. To one portion of the sample solution add a A white (CaC2O4) Ca2+ ion few drops of Ammonium Oxalate {(NH4)2C2O4 precipitate formed confirmed. } solution. dissolves in Con. HCl. A white (Ca(NH4)K[Fe(CN)6] Another portion is made “neutral” by precipitate. adding NH4OH followed by boiling Note: till smell of NH3 is gone. Cool this Ca2+ ion  Only a ‘neutral’ solution solution and then add 2 drops of confirmed. answers this test. NH4Cl and few drops of K4[Fe(CN)6]  If the medium is acidic or solution. alkaline, the test fails. 2020-21 Page 5 of 6  INDIAN SCHOOL MUSCAT SENIOR SECTION DEPARTMENT OF CHEMISTRY CLASS XI-LAB SHEET REPORT: The given sample has: - Cation: ……….……….………, anion: ……….……………….and the salt is ….... ………………….…………………………… Note: Use only ionic and molecular formulae for reporting NOTES & USEFUL INFORMATION: 1. Always record the analysis in a tabular form. (i. e. draw three columns for recording “Experiment’, ‘Observation’ and ‘Inference’) 2. Give continuous serial numbers to tests while recording the analysis in your book. 3. “Notes” given in this ‘analysis handout’ are hints only, hence should not be written in the journal. 4. Some Manganese salts show sparking flame when flame test is conducted. 5. “DANGER!” Hot concentrated reagents should not be thrown into sink. {Cool the out side of the test tube to room temperature under running tap water and then carefully dilute the mixture by adding tap water little by little. Once the mixture is safely diluted, it may be washed normally.} 6. Whenever solubility of a precipitate formed is tested, a small amount (a drop) of the precipitate should be transferred to another test tube and dissolve in excess amount of solvent. (Always show two test tubes for attestation of the work) 7. When chloride ion is detected with Cu2+ or Mn2+ ions, AgCl will not give a clear transparent solution with excess of NH4OH (Solubility part of the 2nd confirmatory test). This may be avoided by washing the precipitate: [Centrifuge the mixture and discard the rest of the solution to separate AgCl. Add distilled water to the centrifuge tube, shake well to wash AgCl. Centrifuge again and discard water. Use the washed AgCl to do solubility test with NH4OH.] 8. Nessler’s reagent test should be conducted only after identifying the presence of NH4+ ion using NaOH test. (Zn2+ & Mn2+ ions can also give brown precipitate with Nessler’s reagent) 9. Confirmatory tests for cations can also be done using true solutions made from the precipitate obtained during Inter-group separation of the cation in suitable solvents. 10. Only Green or Blue salts will give black precipitate with H 2S gas. If black precipitate is obtained with salts that are not blue or green it is due to contamination of the solution and should be rejected. 11. #  Sodium Bismuthate solution: The reagent shows tendency to settle as it is sparingly soluble in distilled water. So whenever the reagent is used, do shake the reagent bottle well before transferring the reagent. Otherwise only supernatant water will get transferred to the test tube. 12. Second confirmatory test for Ni2+ ion may fail if Br2 water used is weak. 13. If chloride ion is confirmed with Calcium ion: Neutralisation has to be compulsorily done as CaCl2 shows acidic character. 14. 2nd confirmatory test for Ca2+ ion: If the sample does not dissolve in distilled water, the true solution made should be properly neutralised as per the instruction given. 15. Write completed salt work in the Journal only after getting it corrected in the observation note book. 2020-21 Page 6 of 6