Materials and Equipment:

- Test tube (10), 10-mL                - 6 M Sodium hydroxide (NaOH), 20 mL

- Test tube rack                          - 6 M Ammonia (NH3), 20 mL

- Pipet, graduated, 10-mL             - 0.1 M Potassium chromate (K2CrO4), 20 mL

- Rubber bulb                              - 1% Aluminon dye, 2 mL

- Pipet, plastic (7), 1-mL               - 6 M Hydrochloric acid (HCL), 20 mL

- Centrifuge                                - Dimethylglyoxime (DMG) reagent, 5 drops

- Beaker, 250-mL                         - 0.2 M Potassium ferrocyanide (K4[Fe(CN)6]), 2 mL

- Evaporating dish                        - 3 M Sulfuric acid (H2SO4)

- Stirring rod                               - 3% Hydrogen peroxide (H2O2), s mL

- Hot plate                                 - Unknown cation solution, 20 mL

- Litmus paper (10)                      - Deionized water, 5 mL

- pH paper (1 roll)                        - Marking pen

Methods:

1. Prepare a hot water bath (approximately 80°C).
2. Preform the reactions with your unknown solution according to procedures 1-12.
3. After each procedure, record your observations of each test performed in table 3.
4. After completing procedures 1-12, clean up according to you teacher's instructions.

Procedure 1- Detection of Ammonium Ion:

1. Measure 1 mL of the unknown solution into an evaporating dish.
2. Add 2 mL of 6 NaOH with a pipet and cover with a watch glass with a piece of moist litmus paper attached.
3. Watch for a color change in the litmus paper from red to blue, indicating the presence of ammonia.

Procedure 2- Separation of Silver and Lead as Chlorides:

1. Using a clean pipet, transfer 2 mL of the unknown solution to a test tube.
2. Add 2 to 3 drops of 6 M HCl. If a precipitate forms, continue adding 6 M HCl solution drop by drop while stirring until no more precipitate forms. If no precipitate forms, save the solution for Procedure 6.
3. Centrifuge the mixture in the test tube, and then add one drop of 6 M HCl.
4. If no additional precipitate appears, pour the supernatatnt into another test tube.
5. If more precipitate forms, repeat steps 3-4 until no new precipitate forms.
6. Label the samples and save the supernatant for Procedure 6. Use the precipitate for Procedure 3.

Procedure 3- Separation of Lead Ion form Silver Ion(Continue from Procedure 2):

1. Using a clean pipet, add 3 to 4 mL of deionized water to the precipitate from Procedure 2.
2. Heat the test tube by swirling it in a hot water bath for several minutes while stirring.
3. Centrifuge the test tube to separate the supernatant from any remaining solid.
4. Save the supernatant for use in Procedure 5. Use the precipitate for Procedure 4.

Procedure 4- Confirmation of Silver Ion (Continue from Procedure 3):

1. Add 10 drops of 6 M ammonia solution to the precipitate from Procedure 3 and stir.
2. Add 6 M HCl drop by drop until the precipitate reappears or until the litmus paper indicates the solution is acidic.

Procedure 5- Confirmation of Lead Ion (Continue from procedure 3)

1. If the solution from Procedure 3 contains a precipitate, re-heat the solution in the hot water bath until the precipitate is completely dissolved.
2.  Divide the sample into two test tubes. Add several drops of 3 M H2SO4 to one of the test tubes.
3. Add several drops of potassium chromate to the second test tube and stir.

Procedure 6- Precipitation of Nickle, Magnese and Iron Ions as Hydroxide(Continue from Procedure 2):

1.  Add 6 M NaOH to the supernatant from Procedure 2 until the precipitation is complete.
2. 2. Add 0.5 mL more of the NaOH and stir.
3. Separate the supernatant from any precipitate. Save the supernatant for Procedure 11. Use the precipitate for Procedure 7.

Procedure 7- Separation of Nickel Ion from Manganese and Iron Ion (Continue from Procedure 6):

1. Add 3 mL of 6 M ammonia and stir well.
2.  Separate the supernatant from any precipitate. Save the supernatant for Procedure 10. Use the precipitate for Procedure 8.

Procedure 8- Confirmation of Manganese Ion (Continue from Procedure 7):

1. Add 1 mL of 3% hydrogen peroxide to the precipitate from Procedure 7.
2. Stir, then heat the sample in the hot water bath until no more gas is produced.
3. Add 3 M H2SO4 drop by drop until the mixture is acidic.
4. Separate the supernatant from any precipitate and use it for Procedure 9.

Procedure 9- Confirmation of Iron Ion (Continue from Procedure 7):

1.  Add two drops of 0.2 M K4[Fe(CN)6] to the solution from Procedure 8.

Procedure 10- Confirmation of Nickel Ion (Continue from Procedure 7):

1. Add 1 drop of 6 M HCl. Then add 5 drops of dimethylglyoxime reagent to the solution from Procedure 7.

Procedure 11- Detection of Aluminum Ion (Continue from Procedure 6):

1. Neutralize the solution from Procedure 6 by adding 3 M H2SO4. Use the pH paper to test the pH after adding each drop.
2. Add 2 more drops of 3 M H2SO4  after obtaining a neutral pH. Use the supernatant for Procedure 12.

Procedure 12- Confirmation of Aluminum Ion (Continue from Procedure 11):

1.  Add 2 drops of aluminon dye to the solution from Procedure 11.
2.  Add the 6 M ammonia drop by drop while stirring. Use the litmus paper to detect when the solution is basic and then stop adding the ammonia.