Seperation and Qualitative Analysis of Cations Post Lab Please help me finish th

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Seperation and Qualitative Analysis of Cations Post Lab

Please help me finish the questions that have not be crossed out, I only have until the ned of the night and my final grade depends on it. PLEASE I WILL LOVE YOU

1. Describe the process by which Ag+ ions are precipitated out of solution.

2. A disproportion reaction occurs when NH3 solution reacts with Hg2Cl2. Write a balanced reaction equation for this event.

Here is the lab procedure:

I know its a lot to digest, but it would mean the WORLD to me if you could help me finish these questions.

PROCEDURE Separation and Analysis for Cations I. Obtain and wear goggles 2. set up 10 test tubes in a test-tube rack. Label the test tubes th1-10. Prepare a hot water bath in a 250 mL beaker 3. Prepare a known solution in Test Tube 1 by mixing three drops of each ion that you wish to test. You will have about 2 mL of solution Analyze the Solution for the Presence of Pb Hg2 and Ag ions 2+ 4. Add 8 drops of 6 M HCl solution to Test Tube 1 and stir the mixture. If a white precipitate forms, then one or more of the following ions are present: Ag and/or Centrifuge the test and add more drop of 6 M HCl. No additional precipitate should more precipitate does form, continue adding HCl e drop at a time the supernatant remains clear. 5. Centrifuge the mixture and transfer the supernatant liquid to Test Tube 2 6. Add 1 mL of distilled water to Test Tube 1, containing the precipitate. Stir the mixture, centrifuge the test tube, and decant the wash water down the sink 7. Test the precipitate for Pb2+ ions by first adding 1 mL of distilled water to Test Tube 1. Place Test Tube 1 in the hot water bath, which should be at or very near boiling, for about minutes. Stir the test every thirty seconds or so. Centrifuge the hot liquid and quickly into Tube 8. Add 5 drops of 6 M 4 to Test Tube 3. If are lead ions present, a white precipitate will there ions, repeat Steps 7 and 8 with Test Tube 1 to form in the test tube. If you find Pb2 remove all of the lead (II) ions from the precipitate. Continue until the addition of sulfuric acid does not form a white precipitate. Dispose the sulfate precipitate, from Test Tube directed. Status Check At this point in your analysis, you should have three test tubes in use. Test Tube 1 a 2+ contains a precipitate, which you have tested for Pb ns. Test Tube 2 contains a liquid, which is th Pb ions. from Test Tube Test Tube 3 has been used to conduct the test for the presence of Rinse and clean Test Tube 3 2+ reci H3 solution to Test dark gray precipitate forms, then Hg2 2+ ions are present. Stir the mixture and centrifuge the

Explanation / Answer

(1)

Ag+ ions in the solution can be precipitated by adding 6.0 M HCl (given) as follows.

Ag+ (aq.) + HCl (aq.) ---------------> AgCl (s) + H+ (aq.)

(2) The dispropotionation reaction between Hg2Cl2 and NH3 can be written as,

Hg2Cl2 + 2 NH3 -----------> Hg + HgNH2Cl + NH4Cl

+1 -1      -3 +1               0      +2-3+1-1   -3+1-1                 (oxidation states)

Here, one of the elements, Hg, undergoes both oxidation (Hg+ to Hg2+) and reduction (Hg+ to Hg0) simultaneously. So, it is a disproportionation reaction.

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