For experimental purposes, i chose to focus more on the penny made before 1982 that had a. Percent error for post1982 pennies actual % zinc is 97. In the students experiment, the mass of a sample of molybdenum sulfide, moxsy. To simulate the percentage of each isotope of a specific element when given the weighted average of all naturally occurring isotopes.
But just as elements have one or more isotopes with different masses, the pennies in circulation have different masses. In an object composed of multiple materials like a penny, the density d is a weighted. What must you measure in order to determine the density of a penny. In this activity, the percentage of copper and zinc in post1982 pennies will be determined. Find the mass of 10 pre1982 pennies and 10 post1982 pennies. The objective of this experiment was to check if the fabricator that makes the coin planchets is putting the right amount of copper and zinc into the pennies. Take a file and carve away the layer of copper on the outside rim of the post1982 penny. Obtain a post1982 penny and lightly clean it with steel wool. Determine and record the mass of the post1982 penny. The pre1982 and post 1982 pennies have all been mixed together. After 1983, the us mint changed the composition of the penny to be 97.
By comparing the densities of pennies minted before 1982 and after 1983, we will demonstrate that the composition of these pennies is. Plot of the density of cuzn composites verses composition. Copper is one of the elements from the coinage group in the periodic table with ag and au. October 22, 2017 ap chemistry copper composition of a post1983 penny purpose. Was the mass of 20 pennies equal to 20 times the mass of one penny. We then ran the solution through a spectrometer along with 4 other copper solutions with known concentrations to determine the. What measurable property distinguishes a pre82 penny from a post82 penny. Because of the different compositions of the pre1982 and post1982 pennies, the coins differ in. Mass percentage of copper in pre and post 1982 pennies prepared by. In this experiment, you will use a graph to determine the density of post1983 pennies. The current us penny is made of metallic copper cu plated onto a zinc zn core. Isotopic pennies prelab read the lab handout carefully and answer the following questions. Treasury was losing money in the production of pennies. The purpose of this lab is to accurately determine the densities of pre 1982 and post1982 pennies.
In this experiment, a post 1982 penny was dissolved in nitric acid. Penny lab name the familiar lincoln penny has been made of 95% copper from 1909 1982. For instance if the penny was made between 1944 1982, then it is made of 95% copper and 5% zinc, while if made after that, the penny will be made of 2. Todays penny is quite different from the penny of a decade ago. Thus, the melting point of a post82 penny will be much lower than a pre82 penny. The change in composition of the penny also changed its weight.
Your task is to determine the isotopic composition number of pre1982 and number of post1982 of the element. In 1982, with inflation, the copper in the penny cost more than a penny was worth. Why would someone with a pre1982 penny have a different result than someone with a post1982 penny. You can expand on this experiment by testing pennies from 1982 only. Use the least squared fit to compare and analyze scientific data. Calculate the fractional abundance of each isotope in your sample. Work with one set of pennies at a time, either pre1982 or post1983. Ps chemistry name period labisotopic pennies background. These differences in the composition of older and more recently minted pennies have. So the united states mint began to produce pennies that contained a zinc core. In 1982, the composition of pennies was changed to a solid zinc core with a thin copper. Pennies minted before 1982 are composed of 95 percent copper and 5 percent zinc.
It is believed that a change in the composition of pennies was made in 1982 to make them lighter. The united states government changed the composition of the penny at this time because of an increase in the price of copper. Treasury needed to change no pun intended the composition of the penny. Pennies dated after 1982 simply have a zinc core with a copper surface. We will determine the mass and volume of pennies minted prior to 1982 and pennies minted after 1982, separately and compare their densities. Calculate the percent composition of the element pennium from your data. Its theorized that the 1982d small date copper penny was created when a brass planchet, or prepared coin blank, was left in the mints coin hopper by accident and was inadvertently fed into the coining presses at least one and perhaps many more were unknown until the first one was discovered by paul malone on november 23, 2016. C 12 m concentrated hydrochloric acid muriatic acid. Ap chemistry lab handout 01 per cent copper in a penny. In this lab, you will determine and compare the density of two sets of pennies by graphing mass vs. Post1982 penny composition is 97% zinc with a thin coating of copper. Since then, they have been made with an outside coating of copper and an inner core of a different metal. T a brief history of the us onecent coin penny composition.
In your lab notebook, solve equation 2 for the percent cu p. Chemistry a penny for your thoughts lab alloys background information pre1982 pennies are composed of pure copper. So, in 1982 they changed the penny, and it is now only 2. The amount of copper in the penny decreased in 1982. Percent composition penny lab chemistry physical sciences. What is the mass of the zn deposited onto the copper coins for each current 0.
Classroom resources the captivating chemistry of coins. You should see bubbles begin to form in the glass with the post1982 penny, which. Pennies were being melted down for the value of their metal. All pennies were made with this composition until 1982. The purpose of this lab is to determine the densities of pre1982 and post1982 pennies.
The zinc which was already silver coated the penny. How is it possible that one of them would react with hydrochloric acid but not the other. Record the total number of pennies in the container, the number of pre1982 pennies, and the number of post1982 pennies. Lab report 2 mass percentage of copper in pre and post. There are several ways to distinguish between old and new pennies. Pre1982 penny composition is 95% copper and 5% zinc.
That value can be determined from measurements of the density of the zinc and copper in the penny and their percentages. Background pennies dated up to 1981 are made of copper. Percent composition of zinc and copper in us pennies. Your job is to work with your group to determine the percent composition of a post1982 penny. Cut an old penny and a new penny in half with a pair of tin snips.
Pennies minted after 1982 to the present day are only made up of 2. Header title purpose procedure data graph calculations questions conclusion background information. You will be given a sealed bag containing a mixture of pre1982 and post1982 pennies. The united states penny is composed of copper plated zinc. The penny lab students will design a collect data evidence. Pennies since 1982, however, are made up mostly of zinc. Penny isotopes you will need some paper and a calculator for this lab. Using a triangular file, scrape off the copper coating in two. Measuring the density of pre1982 and post1982 pennies. The purpose of this lab is to accurately determine the. Then use excel to calculate the percent copper of pennies from the calculated average densities of pure copper and pure zinc that you measured. The captivating chemistry of coins american chemical society. The once almost pure copper penny has been replaced with a core of a different base metal that has been copper clad. A team of doctors found that children who swal low post1982 pen nies may.
Percent composition penny lab free download as pdf file. These elements are unreactive and therefore hold up well in use. After 1982, pennies were composed of an inner core alloy of 99. If there was any leftover zinc in your product at the end of your experiment, it could have been dissolved with hydrochloric acid. Isotopes of pennium temecula valley unified school district. Mass pe pre1982 x 100 mass pe post1982 x 100 total mass total mass analysis and questions. In 1982 the composition of the penny was changed from being one of nearly pure copper to that of a zinc. Before 1982, pennies were made of an alloy of copper. These changes to metal composition provide opportunities to explore whats on the.
This copper is plated onto a zinc core that makes up 97. In this lab, we determined the copper composition of a post1983 penny by isolating the copper in the penny and creating a solution with an unknown concentration with that copper. Please consult your current flinn scientific catalogreference manual for. The purpose of this lab is to accurately determine the densities of pre1982 and post1982 pennies. After completing this experiment, the student should be able to. Lab report 2 mass percentage of copper in pre and post 1982 pennies prepared by kyla walker lab partner lisebeth jules lab completed and lab report. Your bag could contain any combination of the two isotopes.
These copper rich pennies are currently worth more as a metal source than their face value. Pass the pieces around so students can see the zinc core in new pennies. Electronic balance, pennies 10 pre1982 and 10 post1982, graduated cylinder 100ml, water procedures. Weigh a pre1982 penny and a post 1982 penny to the nearest 0. Introduction with the rising cost of mineral resource the composition of the humble penny has change over the years.
Determining the density and composition of pennies statement of purpose todeterminethedensityandthecompositionofpre1982andpost1982uspennies. To determine the percent composition of copper in a penny. Different compositions can have significantly different masses. Then, you will use known density values to identify the metal used in the core of these pennies. The reaction was to be observed and samples were to be collected for examination. However, the price of copper had risen so much that the u. Repeat the experiment after telling students to listen very. After 1982, pennies were made of zinc with a copper coating.
On april 2, 1792, congress established the united states mint and began to produce copper pennies. Ap chemistry lab 4 3 using beers law to determine the mass percent of copper in an alloy measuring the unknown 6. In 1982 the composition of pennies was changed because they contained more than 1 cents worth of copper. Penny compositionpenny composition pennies made from 1962 to 1982 consist of 95% copper and 5% zinc. As a result, there were nationwide penny shortages due to incessant hoarding.