1. Classify a penny minted in 2005 as a pure substance or a mixture. If you select pure substance, is the penny an element or a compound? If you select mixture, is the penny homogenous or heterogeneous? Be sure to justify your answer.
2. What happened to the mass of the pennies from 1962-2009 in the class data set? Describe any trends and provide an explanation for the data obtained.
3. The composition of the penny from 1962-1981 was 95.0% copper and 5.0% zinc by mass. After 1982, pennies were made with a zinc core coated with copper changing the overall composition to 2.5% copper and 97.5% zinc. State the literature densities of copper and zinc (ref 7). How well do your calculated densities (part C) match the literature values for copper and zinc? Should they match? Why or why not? (A good answer should include a chart with both your values and the lit. values followed by a logical commentary. Use full sentences.)
4. Report the actual mass and volume of a post-1982 penny from the U.S. Mint webpage (ref 6). Make a table to compare your measured mass and volume values from your post-1982 penny to the actual values. The following equation may be helpful: volume of cylinder =pi*r^2*h (hint: convert mm to cm before using the formula)
5. 5. The hypothesis in part C stated: The chemical composition of the penny changed after 1982. Besides finding the density of the penny, what ELSE could you do? Propose at two possible experiments to test this hypothesis. Describe the experiments briefly (a sentence or two). Do not suggest mass, volume or density - we did this already.

Class Data and Graph: (ins \begin{tabular}{|r|r|} \hline Time (yr) & Mass (g) \\ \hline 1964 & 3.082 \\ \hline 1969 & 3.074 \\ \hline 1970 & 3.008 \\ \hline 1971 & 3.111 \\ \hline 1973 & 3.077 \\ \hline 1975 & 3.093 \\ \hline 1977 & 3.095 \\ \hline 1978 & 3.086 \\ \hline 1979 & 3.101 \\ \hline 1981 & 3.101 \\ \hline 1983 & 2.534 \\ \hline 1987 & 2.561 \\ \hline 1991 & 2.510 \\ \hline 1993 & 2.514 \\ \hline 1996 & 2.497 \\ \hline 1998 & 2.498 \\ \hline 2000 & 2.499 \\ \hline 2002 & 2.503 \\ \hline 2004 & 2.503 \\ \hline 2007 & 2.504 \\ \hline \end{tabular} \begin{tabular}{|c|c|c|l|} \hline Penny \# & Mint Year & Mass (g) & \multicolumn{1}{|c|}{ Observations } \\ \hline 1 & 1978 & 3.051 & Dull and has minor dark spots with texture. \\ \hline 2 & 1978 & 3.078 & Back side is worn, less shiny and can barely read letters. \\ \hline 3 & 1978 & 3.070 & Tarnished and there was dent on side of edge. \\ \hline 4 & 1978 & 3.064 & Front side is less shiny and Lincoln face was worn out. \\ \hline 5 & 1978 & 3.093 & Tarnished and has two dark spots on the front. \\ \hline 6 & 1978 & 3.115 & Minor dark spots and tarnished. \\ \hline 7 & 1978 & 3.074 & Big black spots on back side, and dull. \\ \hline 8 & 1978 & 3.090 & Tarnished, has brown marks on back. \\ \hline 9 & 1978 & 3.109 & Dull and has minor dark spots on back side. \\ \hline 10 & 1978 & 3.117 & Feels heavy, front edges worn down. \\ \hline 11 & 2004 & 2.516 & Dark spots on back side. \\ \hline 12 & 2004 & 2.493 & Muddy on back side and minor dark spots on front. \\ \hline 13 & 2004 & 2.492 & Tarnished, has dark spots on back side. \\ \hline 14 & 2004 & 2.487 & Dull and hard to see details on front. \\ \hline 15 & 2004 & 2.550 & Tarnished with minor dark spots on the front side. \\ \hline 16 & 2004 & 2.504 & Less shiny on front side and a big black spot on back. \\ \hline 17 & 2004 & 2.481 & Back side is worn and dull. \\ \hline 18 & 2004 & 2.497 & Large smear on back and tarnished. \\ \hline 19 & 2004 & 2.505 & One blue residue on front. \\ \hline 20 & 2004 & 2.505 & Dull and minor dark spots on front. \\ \hline \end{tabular} Part B: Volume Hypothesis: The size of the penny decreased after 1982. Method Used: Ruler Method Sample Calculation: V=r2h Year =1978 Volume =0.444ml Year =2004