`Just How Thick Is Aluminum Foil Anyway???Patricia A. Riley              Lincoln Park High School                               2001 N. Orchard Street Mall                               Chicago, IL 60614                               312-534-3180Objective:      To determine the thickness of a sheet of aluminum foil from the density of  aluminum metal. Materials needed:     Class:                                        Each group of 2 or 3:aluminum metal shavings                    balancevariety of brands of aluminum foil         metric rulerdemonstration vernier caliper              vernier caliperrolling pin                                rectangular aluminum metal slabgraduated cylinder, 50 mL                  rectangular piece of aluminum foilStrategy:   1.  Pass 3 or 4 different brands of aluminum foil in boxes (e.g. Reynolds Heavy Duty, Reynolds Aluminum Foil, Heritage House Heavy Duty, generic aluminum foil, etc.) around for students to examine.  Ask in what ways the brands differ from each other.  What is meant by "heavy duty"?  Net weight and the foil thickness are not printed on the boxes.  Ask students for suggestions for determining these.    2.  Review the use of a vernier caliper using the large demonstration model and boxes of the foil.  Ask students to come up and read the calipers.  Would the calipers be useful in finding the foil thickness?  They should explain.    3.  Review the concept of density which relates the mass of the substance to its volume.  What is the mathematical formula for density?  Does density depend on the shape of the solid aluminum?  Show students aluminum shavings and a rectangular aluminum slab.    4.  Have students test out their answer for density by finding the density of a rectangular aluminum slab at their lab station, recording their data and calculations in their lab notebook and then writing their experimentally determined density on the board.  Determine the class average density for the aluminum slabs and compare it to the experimental value for the aluminum shavings that they determined in an earlier lab.  Have a student look up the theoretical density for aluminum in the CRC Handbook of Chemistry and Physics.    5.  Now have the students experimentally find the thickness of their piece of aluminum foil, recording data and calculations in their notebooks.  All groups have the same brand and thickness of foil.  Have a rolling pin and graduated cylinder available for students wishing to verify the volume by water displacement.  Record their answers on the board and calculate the average.    6.  Students write answers for the following questions in their lab report:       A. What precautions must be taken when massing the foil?       B. Why won't water displacement work well for finding the foil's volume?       C. You are given a chunk of shiny silver-colored metal.  How can you           tell whether the metal is silver, platinum or aluminum?       D. Describe how the thickness of the metal in the side of an aluminum           pop can can be determined.       E. From the information printed on the box of the aluminum foil, describe          how you might verify your experimentally determined foil thickness. `