Penny Lab Report - Chem 125 Penny Lab Report Purpose and...

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Chem 125 Penny Lab Report Purpose and Hypothesis: The purpose of this experiment was to find if the composition of a post- 1962 penny has remained constant throughout the years. We were also testing to see what material(s) the pennies in 2006 are now composed of. We were informed before our experiment of the many changes the composition of the penny has gone through over the years. The longest duration of time that one composition of a penny has stayed around was 98 years and the composition has changed at least 5 times from 1793-1962. After being told this information we hypothesize that the composition of a post-1962 penny has not remained the same. We also propose that the new pennies are now made of zinc and are coated with copper because they are not magnetic and copper is too expensive to make a whole penny out of pure copper. Experimental: First we obtained 40 pennies from the years 1990-1999 and separated them by year. One penny, not included in the group of 40 pennies was held under a blow torch at around 900 degrees Celsius. We observed that the top layer of the penny started bubbling and then drops of silver liquid fell from the coin. It hardened very quickly into a shining silver piece and the penny itself was a darker gray. Then, using an analytical balance we weighed our pennies in groups of 4. We chose to weigh them in groups of 4 because we were given exactly 40 pennies with 4 pennies in each year, from 1990-1999. We than took our weights and divided them all by 4 to find the average weight, in grams, of one penny from each year. Then we stacked the pennies, one on top of the other (see figure 1), for each year, giving us ten sets of pennies. We took the cm side of a ruler and measured the height of the stack of pennies. Then we divided that number by 4 as well to find the average height of a penny for each year. Finally, we took the 4 pennies from each year, one at a time, and spread them across the ruler side by side. We measured how wide all 4 pennies were across and then divided that number by 4 as well, to find the average width of one penny from each year, also known as the diameter of each penny. We then also calculated the
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density and volumes of our pennies using, V=pi * r^2 * h and D=M/V. Figure 1: (source #1)
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Penny Lab Report - Chem 125 Penny Lab Report Purpose and...

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