Materials

- 10 post-1982 pennies (4% copper and 96% zinc)
- 10 pre-1982 pennies (100% copper)
- balances
- calculator
- mystery canister

Procedures

- Take the mass of 10 pre-1982 pennies by using a balance and find the average mass of a pre-1982 penny by taking the total mass and divided by 10.
- Take the mass of 10 post-1982 pennies and find the average mass.
- Take the mass of 10 “mystery” pennies in a metal canister.
- Find the mass of the 10 “mystery” pennies by subtracting step #3 by the mass of the canister, which is 78.49g.
- Find the number of pre-1982 and post-1982 “isotope” in the "mystery" sample by using the equation:

X Y + (10 − X) Z = M

Data

mass of 10 pre-1982 pennies ??? average mass of pre-1982 pennies (Y) ??? mass of 10 post-1982 pennies ??? average mass of post-1982 pennies (Z) ??? mass of 10 "mystery" pennies and metal canister ??? mass of metal canister 78.49 g mass of 10 "mystery" pennies (M) ??? number of pre-1982 pennies in the canister (X) ??? number of post-1982 pennies in the canister (10 − X) ??? % of pre-1982 "isotopes" in "mystery" pennies ??? % of post-1982 "isotopes" in "mystery" pennies ???

Analysis

Worksheet