SALT ANALYSIS Anions are divided into 3 Groups 2 NO2 Dil H2SO4 Group CO3 Conc H2SO4 Group Cl Br I NO3 Not identified by i ii Special group SO4 i ii iii S2 CH3 COO 2 SO3 2 C2O4 2 PO4 3 Detection of Anion Two types of tests are to be done in order to detect anion Dry Tests and Wet Tests 1 Preliminary observations a Colour b Structure 2 Dry Tests for Anion Experiment i Action of dil HCl Add 2 c c of dil HCl to the salt 0 1gm taken in a clean and dry test tube ii Action with conc H2SO4 2 cc of conc Sulphuric acid is added to a small amount of salt taken in a clean and dry test tube and heated do not boil the contents gently A pinch of MnO2 is added to the above solution and heated Observation a Colourless odourless gas evolved with brisk effervescence b Turns blue litmus red c Burning splinter is extinguished d Lime water turns milky a Colourless gas is evolved with rotten egg smell b Lead acetate paper turns black a Colourless gas is evolved with suffocating odour b Acidified K2Cr2O7 paper turns green c Acidified KMnO4 paper turns colourless a Light brown gas is evolved with pungent odour b Pass the gas through ferrous sulphate solution it turns brown a Colourless gas is evolved with pungent odour b Turns blue litmus red c Dense white fumes obtained when a glass rod dipped in NH4OH is brought near the gas Greenish yellow coloured gas is obtained which turns starch iodide paper blue black a Reddish brown gas with pungent odour More reddish brown fumes of bromine are evolved when MnO2 is added to the solution and heated b Turns moist starch paper yellow a Violet vapours of iodine are evolved with pungent odour More violet vapours are obtained when MnO2 is added to the solution and heated b Turns moist starch paper blue Inference Gas evolved is CO2 2 confirmed CO3 Gas evolved is H2S S2 may be present Gas evolved is SO2 SO3 Gas evolved is NO2 NO2 2 may be present may be present 1st Gas evolved is HCl 2nd Gas evolved is Cl2 Cl may be present Gas evolved may be HBr Br may be present Gas evolved may be HI I may be present Salt analysis of acid iii Action with conc and Sulphuric ethanol Few ml conc Sulphuric acid is added to a small amount of salt Now few ml of ethanol is added to it and then heated Experiment Test for S2 Add 1 mL of sodium nitro prusside solution to 1 ml soda extract Add 1 mL of lead acetate solution to 1 ml soda extract and acid Test for NO2 Acidify soda extract with acetic add concentrated solution of cobalt chloride Then add KCl solution Warm the contents and wait for some time Test for Cl 1 ml soda extract is acidified with dil HNO3 and then add 1 mL of AgNO3 solution to it Test for Br 1 ml soda extract is acidified with dil HNO3 and then add 1 mL of AgNO3 solution to it Test for I 1 ml soda extract is acidified with dil HNO3 and then add 1 mL of AgNO3 solution to it Test for SO4 2 SO3 2 a Light brown gas with pungent odour b Add Cu turnings and heat Formation of brown gas increases c Turns starch iodide paper blue Gas with vinegar smell A strong Fruity odour of ethyl acetate is obtained Gas evolved is NO2 NO3 may be present Acetate may be present CH3COO confirmed 3 Wet Tests for Anion Wet tests are done with Na2CO3 extract Soda Extract i Preparation of Soda Extract 1 part of salt is mixed with 3 parts of Na2CO3 in a test tube and about 10 15 ml of distilled water is added It is then boiled for 5 minutes taking care that the contents do not boil over It is then cooled filtered and the filtrate is called as Soda Extract ii Confirmatory tests for anion Observation A purple or violet colour is formed Black ppt formed Yellow ppt is obtained White ppt soluble in cold NH4OH Pale yellow ppt is obtained partially soluble in NH4OH CS2 test Acidify about 2 ml of S E with dilute hydrochloric acid Add to it 1 ml of chlorine water or KMnO4 and conc HCl and 4 5 drops of carbon disulphide Shake vigorously Yellow ppt insoluble in insoluble in NH4OH CS2 test Acidify about 2 ml of S E with dilute hydrochloric acid Add to it 1 ml of chlorine and 4 5 drops of carbon disulphide Shake vigorously Violet colouration is obtained White ppt is obtained which is insoluble in dilute HCl Inference S2 confirmed S2 confirmed NO2 confirmed is Cl confirmed Br confirmed I confirmed SO4 2 confirmed 2 Salt analysis acid 1 ml soda extract acidify with dil HCl BaCl2 solution Test for NO3 1 ml soda extract 1ml dil Acetic freshly prepared FeSO4 sol add conc H2SO4 along the side of the test tube Test for CH3COO 1 ml soda extract dil neutralized Mineral acid neutral ferric Chloride solution heat with 2 Test for C2O4 Acidify a portion of sodium extract with acetic acid and add calcium chloride solution Filter the ppt from the above and extract with dilute sulphuric acid Now few drops of KMnO4 solution and warm it 3 Test for PO4 Take about 2 ml of SE add to about 1 ml of conc HNO3 and heat to boiling Now add ammonium molybdate and heat again solution SE is first acidified with dilute acetic acid silver and then nitrate is added to it solution White ppt is obtained which is soluble in dilute HCl SO3 2 confirmed Brown ring is formed at the junction of two liquids NO3 confirmed Wine blood red coloration which turns into reddish ppt on heating CH3 COO confirmed A white precipitate is obtained Pink colour of KMnO4 is discharged 2 C2O4 confirmed is Yellow ppt or colouration is obtained Yellow precipitate is obtained which is soluble in dilute nitric acid PO4 3 confirmed Cation is to be detected are divided into the following groups Group Zero Gp 1 Gp 2 Gp 3 Gp 4 Gp 5 Gp 6 Group Reagent NaOH Dil HCl H2S in acidic medium NH4Cl NH4OH NH4Cl NH4OH H2S NH4Cl NH4OH NH4 2CO3 NH4Cl NH4OH excess Na2HPO4 Mg2 Cations NH4 Pb2 Pb2 Cu2 Fe3 Al3 Zn2 Mn2 Ba2 Sr2 Ca2 excess 3 Salt analysis 4 Preparation of ORIGINAL SOLUTION OS The solubility of the salt mixture should be tested in the following order i ii iii iv v vi In cold water and then hot water Dil HCl first in cold and then in hot Conc HCl first in cold and then in hot Dil HNO3 Conc HNO3 Aqua Regia 3 parts conc HCl 1 part conc HNO3 A saturated solution 10 15 ml is made which is called as the Original Solution 5 Group analysis and confirmatory tests for cation Observation Gas with ammonia smell Moist red litmus turns blue Dense white fumes …