Redox Reactions

In this experiment, you will develop four different activity series--one each for selected halogens, halide ions, metals, and metal ions. You will do this by performing several different reactions involving the pure element and solutions containing their ions. Please refer to your text for additional background information. Goggles are required in this experiment!

Procedure

Part 1

1. This part should be performed under a hood.
2. Place 10 drops of the three different halogen solutions into separate small test tubes. Add 10 drops of cyclohexane to each solution. Stopper the test tubes and shake vigorously for a couple seconds. Record the color of the cyclohexane layer for each halogen. The color of this layer will tell you which halogen is present in the solution. 
3. Discard the contents into the Student Products container labeled for halogenated organics.
4. Into a small test tube, combine 10 drops of a halogen solution with 10 drops of a 0.2 M halide ion solution. Add 10 drops of cyclohexane to the solution. Stopper the test tube and shake vigorously for a couple seconds. Record the color of the cyclohexane layer.
5. Repeat the previous step until every possible combination of a halogen solution and halide ion solution has been made. (Note: Do not react the halogens with their corresponding halides.)
6. Discard the contents into the Student Products container labeled for halogenated organics. Clean your test tubes.
7. Determine the combinations that produced reactions and the ones that did not.

Part 2

1. Obtain a 48-well reaction plate. Obtain seven pieces each of six different metals: Cu, Zn, Pb, Fe, Mg, and an unknown metal. Place each piece of metal into a separate well. 
2. React each metal with each of the following solutions: 0.1 M CuSO₄, 0.1 M ZnSO₄, 0.1 M Pb(NO₃)₂, 0.1 M FeSO₄, 0.1 M MgSO₄, 0.1 M AgNO₃, and 6 M HCl by adding enough of the solution to fill the reaction well half-full (about 15-20 drops).
3. Allow the reaction plate to sit for a few minutes. Then determine the combinations that produced reactions and the ones that did not.
4. Empty the contents of the reaction plate into the designated Student Products container. Clean the reaction plate.

Part 3

In this final part, you will determine the effect of varying the pH on the products of the reaction between the permanganate ion, MnO₄^-, and the sulfite ion, SO₃^2-. To help you identify the products, you may use the following guidelines: 

• The manganese (II) ion, Mn²⁺, is faint pink in color, though it will appear colorless at the concentrations present in this reaction. Manganese (IV) oxide, MnO₂, is a brownish-black solid that is insoluble in water. Finally, the manganate ion, MnO₄^2-, is a green ion in aqueous solution.
• The sulfide ion, S^2-, is an ion that is colorless in aqueous solution, but which smells like rotten eggs in acidic solution. Sulfur trioxide, SO₃, is a white (not colorless) gas. The sulfate ion, SO₄^2-, is an ion that is colorless in aqueous solution and has no noticeable odor.

1. Into each of three small test tubes, add 10 drops of 0.01 M KMnO₄. Add 1 drop of 6 M HCl to the first test tube and 1 drop of 6 M NaOH to the third test tube. Then add 10-12 drops of  0.1 M Na₂SO₃ to each of the three test tubes. Record your observations.
2. Empty the contents of the test tubes into the designated Student Products container. Clean the test tubes.

Data Analysis

1. Arrange the halogens by oxidizing strength from strongest to weakest.
2. Arrange the halide ions by reducing strength from strongest to weakest.
3. Arrange the metal ions by oxidizing strength from strongest to weakest.
4. Arrange the metals by reducing strength from strongest to weakest.
5. Compare your results in Parts 1 and 2 (questions 1-4) with literature results. Make the appropriate comparisons and cite the source(s).
6. Write balanced redox equations (net ionic) for each of the combinations in Part 1 that produced a reaction.
7. Write balanced redox equations (net ionic) for five of the combinations in Part 2 that produced a reaction.
8. Write balanced redox equations (net ionic) for each of the combinations in Part 3. In the second reaction, please note that while no acid or base was added, the reaction mixture is slightly basic.
9. Describe the effect of pH on the degree of oxidation or reduction that takes place. Be specific!

Lab Report

The lab report will be due at the time of your final exam unless otherwise specified by your instructor.  For this experiment, follow the Laboratory Report guidelines located at http://webs.anokaramsey.edu/chemistry/chem1062. At your instructor's discretion, you may have the option of submitting an individual report. If you do so, please underline your name.  Follow your instructor's directions for submitting this lab report. (If emailing, use a filename convention of Lastname1 Lastname2 Redox, and a subject line of "Chem 1062: Redox Lab").

For the lab report, you will need to include a title, procedure, results, discussion, and references.  You may use the above data analysis to guide your discussion, but the discussion is a report and should be more than just answering the questions.  It should flow logically as you discuss the lab and the results.