ELECTROCHEMISTRY EXPERIMENT

Part 3: Corrosion

  • Prepare 7 cleaned iron nails as follows: 
    • 	1. pierce a small piece of Zn with a nail;
	2. wrap copper wire around a nail;
	3. wrap copper wire around another nail but this time leave a 
		length of Cu so that you can attach a strip of magnesium ribbon to the copper wire (be sure that the nail is not in contact with the magnesium and that the piece of magnesium is at a distance from the nail);
	4. wrap a piece of tin around a nail;
	5. score a nail with a metal file in more than one place;
	6. wrap a nail around its middle with a thin strip of aluminum foil;
	7. keep one nail intact.
  • Heat 100 mL of deionized water to boiling in a 250 mL beaker.
  • Take the beaker off of the hot plate and stir in 0.7 g of agar until it has dissolved. Then stir in 0.5 g of NaCl, 0.07 g of K3Fe(CN)6, and 1.5 mL of phenolphthalein solution. Stir until all of the solids are dissolved.
  • Cool the gel-indicator solution until it is just lukewarm, or begins to thicken.
  • Arrange your seven nails, 3-4 per dish, so that they do not touch each other. The plain nail should be rested on the lip of the dish so that part of it will be exposed to the air.
  • Pour the agar mixture over the nails so as to cover them (except the one resting on the lip of the dish).
  • Watch the dishes over a period of 20 minutes to an hour. Note the appearance of any colors around the nail assemblies. Record your observations in your notebook.
  • Dispose of the agar gel and nails in the waste containers provided.

    • DO NOT POUR AGAR DOWN THE SINK.

    WORKUP OF INFORMATION

    For this study you will need to determine which nails are undergoing corrosion and which are not. For those not undergoing corrosion, are there any other metals which might be corroding in lieu of iron? Determine the anodic and cathodic reactions for each nail. Be able to explain what is happening in all six situations.

    An electrochemistry report form can be found in your server "hand out" file. This is an Excel workbook with different worksheets for each part of the lab report. Please note that it has all of the usual aspects of a Bailey lab report but in an electronic format.

    This report will be due Thursday, March 12th at the beginning of class.

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