Just How Thick Is Aluminum Foil Anyway???

Patricia A. Riley              Lincoln Park High School
                               2001 N. Orchard Street Mall
                               Chicago, IL 60614
                               312-534-3180


Objective:

      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                    balance
variety of brands of aluminum foil         metric ruler
demonstration vernier caliper              vernier caliper
rolling pin                                rectangular aluminum metal slab
graduated cylinder, 50 mL                  rectangular piece of aluminum foil

Strategy:


   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.