Making Cents Lab
by E.S. Belasic
Objectives:
* to become proficient in using a balance
*to determine the mass of a penny
*to see if there is a change in mass through the decades
*to learn what metals are used in making pennies
*to determine if the value of the penny has decreased (according to metals used)
Materials:
*Pennies sorted by years: up to 1965, 1970, 1975, etc. 5 years, 3 from each year per group.
*Triple Beam Balance with 0.1g bar, or electronic balance
*US Mint Fact Sheet (given out at end of lab)
Pre Lab Questions:
1.What do you think a penny is made of?
2.How much mass do you think a penny has?
Procedure:
1.Record the mass of a penny to the nearest 0.1g
2.Repeat for all 3 of the same year. Record in Table 1
3.Calculate the average mass. Record in Table 1.
4.Continue until all pennies are done.
Data::
Table 1: Penny Mass in grams
YEARMass 1Mass 2Mass 3Average
1971
1972
1973
1974
1975
Table 2: Class data of average penny mass in grams
up to 19601981-1985
1961-19651986-1990
1966-19701990-1995
1970-19751996-2000
1976-1980etc...
Analysis/Results:
1. What was the average mass of a penny for your years?
2. According to our class data, what year(s) had a difference in mass? Support your answer with data.
3. What metal(s) are pennies made of?
4. How much mass does a dollar worth of pennies have? Show your work!
OUT OF CURIOSITY:
1. What is the going rate for the metal(s) used in a penny?
2.If the mass of a penny is different, does the density change? Hint: Density = Mass/Volume
3. Did you know that a dime has less mass than a penny? That 2 pennies have as much mass as 1 nickel? Prove it!
4. More about the US MINT.
Conclusion: 2-3 sentences demonstrating what you learned in this lab.
The Composition of the Cent
Following is a brief chronology of the metal composition of the cent coin (penny):
*The composition was pure copper from 1793 to 1837.
*From 1837 to 1857, the cent was made of bronze (95 percent copper, and five percent tin and zinc).
*From 1857, the cent was 88 percent copper and 12 percent nickel, giving the coin a whitish appearance.
*The cent was again bronze (95 percent copper, and five percent tin and zinc) from 1864 to 1962.
(Note: In 1943, the coin's composition was changed to zinc-coated steel. This change was only for the year 1943 and was due to the critical use of copper for the war effort. However, a limited number of copper pennies were minted that year. You can read more about the rare, collectible 1943 copper penny in "What's So Special about the 1943 Copper Penny.")
*In 1962, the cent's tin content, which was quite small, was removed. That made the metal composition of the cent 95 percent copper and 5 percent zinc.
*The alloy remained 95 percent copper and 5 percent zinc until 1982, when the composition was changed to 97.5 percent zinc and 2.5 percent copper (copper-plated zinc). Cents of both compositions appeared in that year.