CHE102 Julianne Stiene Exp. 22 Flow Chart March 24, 2008 • Set up hot water bath A. Analysis of Group 1 Cations - Place 10 drops of known solution of 20 drops of unknown solution in a 10x75mm or 10x13mm test tube - Test solution with litmus paper - If basic, add 6M nitric acid, HNO3 solution drop-wise until solution is acidic - Add enough acid so that after mixing, blue litmus paper turns red when touched with stirring rod - Add 2 drops of concentrated (12M) hydrochloric acid (HCl) - Stir solution for 5 minutes - Allow precipitate to settle - Add 1 drop of 6M HCl to determine whether precipitation is complete - If precipitation is not complete, stir and add more drops of 6M HCl until no more precipitate is formed - Cool the test tube by dipping it into cold water - Then centrifuge mixture - If sample is still suspended, centrifuge again - If this still doesn’t work, heat the sample in a water bath for a few minutes, thereby promoting formation of larger crystals of solid, which tend to centrifuge more easily
CHE102 Julianne Stiene Exp. 22 Flow Chart March 24, 2008 - Carefully decant the supernatant liquid into another test tube - If solution is not decently carefully and some precipitate is present, centrifuging and decanting must be repeated - Wash the precipitate with a few drops of distilled water - Solid remaining will have liquid around it and it must be removed - Dilute the liquid with a wash liquid (water) - Stir thoroughly to disperse the solid in the wash liquid and to remove foreign ions adhering to the solid - Centrifuge and decant the wash solution into the test tube containing the original supernatant liquid - If unknown , save supernatant for the group 2 analysis in part - Add 10 drops of hot water to the precipitate, stir and hear the test tube in a hot water bath to near boiling - Quickly centrifuge the hot mixture, and decant the hot supernatant liquid into another test tube -
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- Spring '08
- Sulfuric acid, supernatant liquid, Julianne Stiene