The students chose their intial volume to start at 35.0 mL and then after placing the 15 pennies within the cylinder recorded the final volume. The net volume was then calculated and the net mass of the pennies was divided by that number. Analysis: Using the two different methods “Volume Displacement” and “Direct Volume” the densities resulted were compared to the reference values provided. It seems that the “Volume Displacement” method resulted values of density closer to the reference numbers given. It had been expected that the “Direct Volume” method would have been more accurate since dimensions were being given and mathematics could be used to calculate the density, whereas finding the net mass and the net volume gives way for a larger error because measures are being estimated more often. Perhaps it might have been that the pieces used in the direct volume method were not ideal for the volume equation of that shape. In the pennies it seems that sometime in the 1980s the composition of the penny was changed. The mass of the pennies dating before 1980 was greater than those made after 1980. In taking the dimensions of the newest and oldest pennies and calculating the densities of these two, it seems that the oldest penny has a higher density by about 1.3g/mL. The difference in densities between the oldest and newest pennies may be that as the years went on less copper was used in the making of pennies making them less dense. Conclusion: From this experiment the “Volume Displacement” method proved to be more effective in finding the densities of the solids. Pennies sometime in the 80s changed their composition and the amount of pure copper with which they were made. When looking at the reference densities and the position of the elements on the periodic table, a relationship is noticed that as you move from let to right or from top to bottom the elements get denser.
This is the end of the preview.
access the rest of the document.