Pennies And Calorimetry Lab Report

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In this experiment I will prepare a pure sample of an element (copper) by making a copper solution and then plating it out onto a more active metal.

HYPOTHESIS: Because Copper is a more active metal than Iron, I believe the copper solution will plate onto the iron nail.

PURPOSE: The purpose of this experiment is to observe reactions between metals depending on which one is more active and observe how to clean pennies, while making a copper solution.


Two plastic cups

Clover Valley 5% concentrated white vinegar Soap

An iron nail


1 teaspoon measure

About 40 - 50 cm of thin thread

Table salt

42 dull pennies pre-1983 and 8 dull pennies post-1983

SAFETY CONSIDERATIONS: Always think about safety first. Keep a
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What did you observe happening to the pennies? What is their color? How did they change?
I observed a chemical reaction once the salt was added to the vinegar. The pennies started out as a dull red/brown color and returned almost back to their full original copper look, however, many of the pennies that were coated with black or green, still had some left on the surface and it was more of a dull shine than shinny like new pennies.
2. Using Google (or other search engine) determine why the pennies became the color they did. (Clue: It is the composition. How did the composition change in 1983?)
The reason pennies before 1983 reacted differently than pennies after 1983 is because pennies before 1983 were almost pure copper (97.5% copper and 5% zinc). Once the composition of pennies changed, they were plated with copper to 97.5% zinc and 2.5% copper. Because of this, zinc will react differently with the solution than a more pure copper would. In addition, the reason the pennies were coated with a bluish green color is to protect the copper from further corrosion.
3. How could you account for what happened to the pennies in terms of a microscopic

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