- Be careful when pouring/ measuring out chemicals, there are a lot of liquids that get transferred. Spills could appear! -Be cautious when using the centrifuge, as it could be a hazard when shaking unevenly. Chemicals:Hazards: 6M, 2M HCl Corrosive to skin and eyes0.2 M K2CrO4solutionIrritant15 M NH4OHIrritant to skin and eyes 16 M HNO3Burn to skin and redness to eyes on contact3% H2O2Corrosive to skin and white spots on skin C2H5NS (thioacetamide solution)Irritant to eyes and skin H2SIrritant to eyes, nose, and skin. NH4C2H3O2 Irritant to eyes and skin Ammonia Corrosive NH4Cl Irritant and combustible NaOH Corrosive to skin and eyes NaBiO3 Irritant with contact with eyes K4Fe(CN)6 Irritant with contact with eyes Procedure: Group 1:Ag+ and Pb2+ 1.Add 5 drops of solution of unknown or known in a 12 mL glass centrifuge tube. And add 5 mL of DI water and mix well. 2.Add 2 drops of 6 M HCl and mix and centrifuge. Keep adding drops of HCl until all the precipitation is in the tube. 3.Afterwards save it and store it as P1, test either Ag+ or Pb2+ or both and also save the decant as D1.
4.Add 15-20 drops of hot water to P1 and stir and then heat the tube by placing it in a beaker full of boiling water and stir for 1 minute. Centrifuge and decant into another test tube very fast. Save the decante which contains Pb2+ for the next step. 5.Cool the decantate from the last step and add 1 drop of 0.2 M K2CrO4. 6.Add 4 drops of 15M NH4OH to the precipitate of Pb2+ and centrifuge and decant into another test tube. To the decantate add 16M of HNO3 drop by drop.
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