Materials and Equipment

• 10 10 mL Test tubes
• Test tube rack
• 10 mL graduated pipet
• Rubber bulb
• 7 plastic pipets
• Centifuge
• 250 mL Beaker
• Evaporating dish
• Stirring rod
• Hot plate
• Litmus paper
• pH paper
• 20 mL of 6 M Sodium hydroxide
• 20 mL of 6 M Ammonia
• 20 mL of 0.1 M Potassium Chromate
• 2 mL 1% Aluminon dye
• 20 mL of 6 M Hydrochloric acid
• 5 drops of Dimethylglyoxime reagent
• 2 mL of 0.2 M Potassium Ferrocyanide
• 3 mL of Sulfuric acid
• 2 mL of 3% Hydrogen peroxide
• 20 mL of unknown cation solution
• 5 mL deionized water
• makring pen

 Main Procedure

1. Make sure all of the materials are clean and identify the number of your unknown solution. Number: 2.
2. Prepare a hot water bath to about 80 degrees C.
3. Perform the procedures below,

Procedure 1

1.  Measure 1 mL of the unknown solution into an evaporating dish.
2. Add 2 mL of 6 M NaOH with a plastic pipet. Attach a piece of litmus paper to the watch glass and cover the evaporating dish with the watch glass.
3.  See if the color of the litmus paper changes from red to blue. This will tell if there is ammonia present.

Procedure 2

1. With a new clean pipet transfer 2 mL of the unknown to a test tube.
2.  Add 2 to 3 drops of 6 M HCl. If a precipitate forms, keep adding the HCL drop by drop while stirring until the precipitate stops forming. If no precipitate forms salve the solution for procedure 6.
3.  Centrifuge the mixture in the test tube and then add one drop of HCl.
4.  If no additional precipitate appears, put the supernatant into another test tube.
5. If a precipitate forms then repeat steps 3-4 until no more precipitate forms.
6.  Use the supernatant for procedure 6 and the precipitate for procedure 3. Because no precipitate formed procedure 6 was done next.

Procedure 6

1.  Add the NaOH to the supernatant from procedure 2 until a precipitate forms.
2.  Add 0.5 more mL of the NaOH and stir it.
3.  Separate the supernatant from any precipitate. Save the supernatant for procedure 11 and use the precipitate for procedure 7.

Procedure 7

1.  Add 3 mL of ammonia and stir well.
2.  Separate the supernatant from the precipitate. Save the supernatant for procedure 10 and use the precipitate for procedure 8.

Procedure 8

1.  Add 1 mL of hydrogen peroxide solution to the solution from procedure 7.
2.  Stir the solution and heat the sample in the water bath until no more gas is formed.
3. Add sulfuric acid by drops until the mixture becomes acidic.
4. Separate the supernatant from any precipitate that formed and use it for procedure 9.

Procedure 9

1.  Add two drops of potassium ferrocyanide to the solution from procedure 8.

Procedure 10

1.  Add one drop of HCl and then 5 drops of dimethylglyoxime reagent to the solution from procedure 7.