I will identify the unknown cations from the alkaline earth metals.

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  1. Title:        Group I & Group II Cation Identification

  1. Purpose:

I will identify the unknown cations from the alkaline earth metals. Threw qualitative analysis.

  1. Hypothesis:

I should be able to identify the unknown cations.

Variables:

Control: Solubility rules & double-displacement reactions based on solubility rules.

Dependent: Unknown Ions in the solution

Independent: Various chemical environments induced to identify unknown

  1. Materials:
  1. Chemicals
  1. 6 M HCl
  2. 12 M HCl
  3. 6 M HC2H3O2
  4. 1 M K2CrO4
  5. 6 M NH3
  6. 6 M HNO3
  7. 3% H2O2
  8. 6 M NaOH
  9. 1 M NaOH
  10. 1 M thioacetamide
  11. 1 M NH4Cl
  12. 0.5 M NaC2H3O2
  13. 0.1 M SnCl2
  14. 0.3 g of solid Na2S2O4 (sodium hydrosulfite)
  15. 0.4 g solid sodium thiosulfate (Na2S2O3)
  1. Red & blue litmus paper
  2. Tap water
  3. Distilled water
  4. Dionized water
  5. Stirring rods
  6. Safety glasses
  7. Test tubes
  8. Balance
  9. Large beaker
  10. 50-ml Beaker
  11. Boiling water bath
  12. Sink
  13. 5-mm length of heavy copper wire
  14. 1-cm length of 24 gauge of aluminum wire
  15. Centrifuge
  16. Hot pads
  17. Metal spatulas
  18. Medicine droppers
  19. Test tube holders

  1. Procedure:

Group I Cations

       Step 1:

  1. Add 0.5 ml 6 M HCl to 3 ml of a sample in the test tube.
  2. Stir well and centrifuge.
  3. Decant the liquid, which may have ions, into a test tube.
  4. Save the test tube for further analysis.
  5. Make sure precipitation for Group I cations was complete by adding 1 drop of 6 M HCl into the liquid.
  6. Wash the precipitate with 2 ml water and 2 drops of 6 M HCl.
  7. Stir well.
  8. Centrifuge and throw away the wash liquid.
  9. Re-wash the precipitate with water and HCL.
  10. Throw away the liquid.

       Step 2:

  1. Add about 4 ml water to the precipitate from Step 1, which contains the chlorides of the Group I cations.
  2. Heat the precipitate in a boiling water bath for at least three minutes.
  3. Stir repeatedly.
  4. Centrifuge quickly.
  5. Decant the liquid, which may have Pb2+, into a test tube.

       Step 3:

  1. Add 2 drops of 6 M acetic acid and 3-4 drops of 1 M K2CrO4 into the liquid from Step 2.
  2. Centrifuge out the solid to help with the identification.

       Step 4:

  1. Wash the precipitate from Step 2 with 6 ml water in the boiling water bath if lead is present.
  2. Centrifuge and test the liquid for Pb2+.
  3. Continue washing until no positive reaction to the lead test is obtained.
  4. Add 2 ml 6 M NH3 to the washed precipitate.
  5. Stir well.
  6. Centrifuge and decant the liquid, which may contain Ag(NH3)2+, into a test tube.
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       Step 5:

  1. Add 3 ml 6 M HNO3 to the liquid from Step 4.
  2. Check with litmus to see that the solution is acidic.

       Step 6:

  1. Add 1 ml 12 M HCl and 0.5 ML 6 M HNO3 to the precipitate from Step 4 if the test for silver ion proved inconclusive.
  2. Heat the solution in the water bath until essentially complete.
  3. Pour the liquid into a 50-ml beaker.
  4. Boil the beaker gently for 1 minute.
  5. Add 5 ml water.
  6. Look for the formation of a white ...

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