Purpose: The purpose of this lab is to calculate the atomic mass of “pennium” using pennies made before 1982 and pennies made 1982 or after.
Hypothesis: The atomic mass of the pennium will be the average of the average masses of a pre-1982 penny and a post 1982 penny.
Procedure:
1. Obtain a bag of pennies
2. Determine the total number of pennies in the bag. Record the value.
3. Sort the pennies by date into 2 piles. One pile should consist of pennies older than 1982, the other pile should include pennies that are 1982 or newer.
4. Count the number of pennies in each pile. Record the values.
5. Take the mass of each pile of pennies. (One measurement for each pile.)
Data: Measurements of the “Pennium” and its two Isotopes
Date Number of Pennies Mass
(in grams) Average Mass (in grams) Relative Abundance (percent) Atomic Mass
(grams)
Total Pennies 20 -------------- ---------- -------- 2.800
Older than 1982 10 30.90 3.090 50 ---------------
1982 or newer 10 25.01 2.501 50 --------------
Calculations:
Average Mass:
Older than 1982- Mass: 30.90 grams Number of pennies: 10
30.90 / 10 = 3.090 grams
1982 or after- Mass: 25.01 grams Number of pennies: 10
25.01 / 10 = 25.01 grams
Relative Abundance:
Older than 1982: 10/20 = 50 percent
1982 or after 1982: 10/20 = 50 percent
Atomic Mass of Pennium
(0.50 * 3.090) + (0.5 * 2.501)
1.545 + 1.2505 = 2.7955
Atomic mass = 2.800 (four sig figs.)
Conclusion:
The purpose of this lab was met because the atomic mass of “pennium was calculated using the isotopes of pennium- the ones that were made before 1982 and the ones that were made 1982 and after. The average mass of a pre-1982 penny was 3.090 grams, and the average mass of a post 1982 penny was 2.501 grams. The relative abundance of the pre 1982 pennies was 50 percent, and the relative abundance of the post 1982 pennies was 50 percent. The atomic mass of pennium that was