Removal of Zinc from Pennies

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Removal of Zinc fromPennies

• Floating Pennies

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Removal of ZINC from Pennies

• Objective
• The different reactivities of copper and zinc to
  Hydrochloric Acid will be used to separate the
  two metals from a post-1983 penny. The percentage
  of zinc and of copper can be calculated as well
  as the economic value of each

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Procedure

• Use a file to make four (4) 1 mm deep scores in
  the pennys edge at 90o apart. Why?
• Determine the mass of the penny
• Place the penny in a 100 ml beaker and add 20 ml
  of 6 M HCl
• Let it sit overnight

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Data of Lab Performed 6/2000
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Percentage of Copper 0.1 g / 2.3 g x 100
4.35 Percentage of Zinc 2.2 g /
2.3 g x 100 95.65
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Questions

• What is an alloy?
• Why did the color of the post-1983 penny change
  as you heat it longer?
• What would happen if you heated other coins?

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Answer 1
An alloy is a mixture of different types of
atoms, generally metals. An alloy can have a
variable composition.
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Answer 2
The color continued to change as more zinc
diffused into copper. Also, the longer it was
heated, the more oxidation occurred.
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Answer 3

• If the coins were made of pure metal, oxidation
  might form on the surface. If the metals were a
  mixture (dime or quarter), an alloy might form