Name:
Period:
Density of Pennies
Procedure:
1. Using the balance, determine the mass of 20 pennies made prior to 1982.
Repeat this measurement two more times. Average the results of the three trials
to determine the average mass of the pennies.
2. Repeat step 1 with pennies made after 1982.
3. Pour about 30 mL of water into the 100 mL graduated cylinder. Record the exact
volume of the water. Add the twenty pennies made before 1982 to the water.
Record the volume of the water and pennies. Repeat this process two more
times. Determine the volume of the pennies for each trial. Average the results of
the trials to determine the average volume of the pennies.
4. Repeat step 3 with the twenty pennies made after 1982.
5. Review your data for any large differences between trials that could increase the
error of your results. Repeat those measurements.
6. Use the average volume and average mass to calculate the average density for
each group of pennies.
7. Compare the average calculated densities with the density of copper found on
page 38 of your book.
Data:
Step 1 mass : Trial 1_______
Trial 2_________ Trial 3 _______ Avg. mass______
Step 2 mass : Trial 1_______
Trial 2_________ Trial 3 _______ Avg. mass______
Step 3- Volume of water Trial 1______ Trial 2 ______ Trial 3_____
a) Volume of water and pennies (prior 1982)
Trial 1______ Trial 2 ______ Trial 3 ________
b) Volume of pennies (Volume of water and pennies – Volume of water)
Trial 1_____ Trial 2 ______ Trial 3 _____ Avg. vol______
c) Volume of water and pennies (after 1982)
Trial 1______ Trial 2 ______ Trial 3 ________
d) Volume of pennies (Volume of water and pennies – Volume of water)
Trial 1_____ Trial 2 ______ Trial 3 _____ Avg. vol______
Step 4- a) Calculation of average density of pennies prior to 1982)
Step 1 average mass/ step 3b average volume) = _________
b) Calculation of average density of pennies after 1982)
( Step 2 average mass/ step 3d average volume) = ____________
Discussion:
1. Why is it best to use the results of three trials rather than a single trial for
determining density?
2. How did the density of the two groups of pennies compare? How do you account
for any difference?
3. Use the results of this investigation to formulate a hypothesis about the
composition of the two groups of pennies. How could you test your hypothesis?