OXIDATION-REDUCTION ACTIVITY SERIES

GENERAL CHEMISTRY ii

OXIDATION-REDUCTION ACTIVITY SERIESLab 8

Bezawit Wube7/8/2013

Objectives: To allow students to observe oxidation-reduction reactions To introduce students to the activity series To allow students to assign Unknown X a place in the activity series

Materials

Paper towelsFrom LabPaq 1 Well-Plate-241 Tweezers, plastic 1 Copper (II) Sulfate, 1 M - 3 mL in Pipet1 Iron (III) Chloride, 2 M - 3 mL in Pipet1 Iron Metal, 2 pc in Bag 2"x 3 1 Magnesium Metal (ribbon) - 2 Small Piecesin Bag 2"x 3"1 Magnesium Sulfate, 2 M - 3 mL in Pipet1 Lead metal, 4 small pieces in bag 2 x 31 Sodium Sulfate, 1 M - 3 mL in Pipet1 Zinc Metal - 2 Small Pieces in Bag 2"x 3"1 Zinc Nitrate, 2 M - 3 mL in Pipet

Procedure:

1. Place 10 drops of Sodium sulfate, Na2SO4 into well A1 of the 24-well plate.2. Place 10 drops of Magnesium sulfate, Mg SO4 into well A2 of the 24-well plate.3. Place 10 drops of Zinc nitrate, Zn (NO3)2 into well A3 of the 24-well plate.4. Place 10 drops of Iron (III) chloride, FeCl3 into well A4 of the 24-well plate.5. Place 10 drops of Copper (II) sulfate, Cu SO4 into well A5 of the 24-well plate.6. Take the metal solids from your LabPaq; there should be one piece each of magnesium, zinc, and iron plus two pieces of lead.7. Use your tweezers to pick up and carefully insert the piece of magnesium into the sodium sulfate. Record your observations.8. Carefully insert a piece of zinc into the magnesium sulfate. Record your observations.9. Carefully insert a piece of lead into the zinc nitrate. Record your observations.10. Carefully insert the lead into the iron (III) chloride. Record your observations.11. In the same way carefully insert the iron into the copper (II) sulfate. Record your observations.12. Based on the above tests alone, you may not be able to determine if iron is more reactive than zinc, or if zinc is more reactive than iron. However, there are enough metal pieces and solutions available to make that determination.13. Place a paper towel over the drain of your sink and pour the contents of the well plate through it. Throw the paper towel and metal pieces in the trash. Rinse the well plate and your drain with lots of running water and return the well plate to your LabPaq.

Data:

Data Table: Oxidation-Reduction

Reactions

Mg in Na2SO4 Good amount of bubbles are observed Mg>Na

Zn in MgSO4 Little bubble is observed Zn> Mg

Pb in Zn(NO3)2 There is no change Zn>Pb

Pb in FeCl3 Lead changes color to greenish / yellowish Pb>Fe

Fe in CuSO4 The iron Is rusted and also black particles underneath the rust Fe>Cu

Questions:

A. Based on your observations make an activity series of the metals used. List them in such a way that the most active metal is on the left and the least active metal is on the right. Remember, sodium and copper are metals, too.

Zn > Pb > Fe > Cu > Mg > Na

B. Suppose you inserted a piece of copper into a solution of nickel chloride and observed no reaction. Then if you inserted a piece of iron into the solution of nickel chloride a nickel deposit formed on the bottom of the well in the well plate. Where does nickel fit into your activity series?

The chemical reactions for the preceding question B are: Cu (s) + NiCl2 (aq) no reactionFe (s) + NiCl2 (aq) 2 Ni (s) + Fe Cl2 (aq)

Fe > Ni > Cu From the second reaction, it can be concluded that iron replaces nickel .

C. Suppose you inserted a piece of an unknown metal into a solution of zinc (II) nitrate and observed no reaction. Then if you inserted the unknown piece of the metal into the solution of iron (III) chloride a deposit formed on the bottom of the well in the well plate. Where does the unknown metal fit into your activity series?

1st step: Zn > unknown metal 2nd step: unknown metal > Fe Overall, it can be concluded: Zn > unknown metal > Fe

For the reaction (Fe (s) + NiCl2 (aq) 2 Ni (s) + Fe Cl2 (aq) identify:

1. The oxidation number of Ni (s)

0

2. The oxidation number of Fe in the FeCl2 (aq)

+2

3. The oxidation number of Cl in the FeCl2 (aq)

-1

4. The oxidation number of Fe (s) 0

5. The oxidation number of Ni in the NiCl2 (aq)

+2

6. The oxidation number of Cl in the NiCl2 (aq)

-1

7. The element that is oxidized and the element that is reduced Fe is oxidized and Ni is reduced

8. The oxidizing agent and the reducing agent

Fe is reducing agent and Ni is oxidizing agent

Analysis:For reaction 1 and 2, both Mg and Zn produce bubbles when combined with SO4. They are displacing SO4.Both Mg and Zn are more reactive than Na.No change is observed in reaction 3. Thus lead does not replace Zn and so is less reactive than Zn.

Conclusion:While doing this lab, students should take extra precaution by wearing goggles and gloves. Students will be able to state if a reaction is a redox reaction or non-redox reaction.Possible error can be when doing the observation, students should be able to tell when there is small bubble; it might be difficult to see right away clearly. Also some reactions might take more than 6 or 7 minutes, so one should wait to see the completion before suggesting that there is no reaction.