The goal of this lab is to find out which metals were used in the minting of pennies before and after 1982 by calculating their densities.

Hypothesis

If the penny was made after 1982 then its density will be higher than those made before 1982.

Materials

• 1 Graduated cylinder

• 30 mL of water

• 10 pennies minted before 1982

• 10 pennies minted after 1982

• 1 electric scale

Procedure

The mass of ten pennies minted before 1982 was calculated five times using the scale and then averaged. These steps were repeated with the pennies minted after 1982. 30 milliliters of water was placed into the graduated cylinder. The pennies minted before 1982 were placed in the water and the new volume was recorded and used to calculate the volume of the pennies. The five calculations were averaged. These steps were then repeated with the pennies minted after 1982. The precision of the mass and volume data was calculated. The mass calculations were divided by the volume calculations to find the densities for both sets of pennies.

Data and Observations

Trial Mass of pennies minted before 1982 Mass of pennies minted before after 1982

#1 30 grams 24 grams

#2 31 grams 24 grams

#3 30 grams 24 grams

#4 30 grams 25 grams

#5 31 grams 24 grams

Trial Volume of pennies minted before 1982 Volume of pennies minted after 1982

#1 4 milliliters 3 milliliters

#2 4 milliliters 3 milliliters

#3 4 milliliters 3 milliliters

#4 4 milliliters 3 milliliters

#5 4 milliliters 3 milliliters

Conclusion

My hypothesis that the pennies made after 1982 would be denser than those minted later was supported by the experiment. The collected data shows that the older pennies have a density of 7.6g/mL ± .5g/mL. This density is closest to the density of zinc, which has a density of 7.19. The newer pennies have a density of 8.07 g/mL ± 1g/mL. This density is closest to the density of nickel, which has a density of 8.85 g/mL. The percent error for the density of the older