Corrosion Lab
Purpose
To investigate and compare the relative reduction potential of copper, lead and zinc.
Background
The rusting of iron and the combustion of gasoline are common examples of oxidation-reduction reactions. Oxidation reactions are also thought to partly responsible for the aging of the human body. Every oxidation reaction involves a transfer of electrons form the substance oxidized to the substance reduced. A substance undergoing oxidation gives up, or losses, electrons; a substance undergoing reduction gains electrons. The ease with which a substance oxidizes depends on the substance. For instance, iron oxidizes more easily than either silver or gold.
In this experiment, you will study some oxidation-reduction reactions that occur between metals and metal ions. On the basis of your experiments, you will organize these substances into a series according to their relative ease of oxidation.
Materials
Safety goggles
9 small test tubes
1 test-tube rack
1 10 ml graduated cylinder
Copper (s)
Lead (s)
Zinc (s)
0.1 M copper (II) nitrate
0.1 M lead (II) nitrate
0.1 M zinc nitrate
Procedure (READ THE ENTIRE LAB BEFORE BEGINNING)
As you perform the experiment, record your observations in the date table
1. Label three test tubes 0.1 M Cu(NO3)2. Add 3 ml of 0.1 M Cu(NO3)2 to each test tube. In one tube place a strip of copper. In another, place 2.0g of lead. In the third place 1.0g of zinc. Put the tubes in a test-tube rack.
2. Labeling three test tubes 0.1 M Pb(NO3)2. Add 3 ml of 0.1 M Pb(NO3)2 to each test tube. In one tube place a strip of copper. In another, place 2.0g of lead. In the third place 1.0g of zinc. Put the tubes in a test-tube rack.
3. Labeling three test tubes 0.1 M Zn(NO3)2. Add 3 ml of 0.1 M Zn(NO3)2 to each test tube. In one tube place a strip of copper. In another, place 2.0g of lead. In the third place 1.0g of zinc. Put the tubes in a test-tube rack.
4. Allow the test tubes to stand undisturbed for 10 minutes.
5. While waiting for the reaction to occur, in Data Table 1 record your predictions based on the relative strength of oxidizing and reducing agents from the text. Determine which metals will reduce another metal in solution.
6. Record your actual observations in Data Table 2. Briefly describe evidence of any reaction.
7. Clean and dry any metals that did not react and return them to the teacher for reuse.
8. Solids that did react go in the trashcan.
9. Clean and replace all other lab equipment.
Data Tables
Table 1: Reactions of Metals and Metal Ions PREDICTIONS
Cu2+ / Pb2+ / Zn2+Cu (s)
Pb (s)
Zn (s)
Table 2: Reactions of Metals and Metal Ions OBSERVATIONS
Cu2+ / Pb2+ / Zn2+Cu (s)
Pb (s)
Zn (s)
Analysis and Conclusions
1. Write balanced equations for any reactions that you observed between solid metals and metal ions. What type of reactions are they?
2. Which metal was oxidized by both of the other two metals?
3. Which metal was oxidized by only one of the other two metals?
4. Write balanced half-reactions for the reduction of each of the three metal ions used in this experiment. Write the equations so that the metal ions are shown as reactants and the solids metals are shown as products. List these half-reactions so that the most easily oxidized metal is given last.
5. The relative ease the oxidation of the halogens is in this order: chlorine, bromine, iodine, with iodine the most easily oxidized. Design an experiment that would allow you to determine if the halogens are less or more easily oxidized than the metal used in this experiment.