Saving pre-1982 Copper Pennies (Investing or staving an economic tumble)
From to the present, U.S. pennies have been made either mostly of copper or mostly of zinc: Brass pennies (made of 95% copper and 5% zinc) weigh grams Copper-plated zinc pennies (made of % zinc, % copper) weigh grams. But, before I do, hereТs more info on penny values: No Mintmark (Philadelphia) penny Ч 7,,, ( billion) minted Ч 10 cents to 25+ cents D (Denver) penny Ч 6,,, ( billion) minted Ч 10 cents to 25+ cents S (San Francisco) proof penny Ч .
Abstract: The percent composition of copper was analyzed for both pre and post pennies. This was determined by iodometric titration analysis. In how many atoms in dna experiment, two pennies were analyzed.
One of the pennies was pre while the other was post mase This was performed due to the change in the amount of copper used for pennies after Afterelectroplating techniques were used to help the government save money. Due to the high price of copper, the penny was changed to contain 2. In our experiment, to determine this copper content of the pennies, they were dissolved in sulfuric acid and an iodometric titration was performed.
Iodometric titration uses the reaction of copper II by the iodide ion. The addition of thiocyanate ensures that this reacts with the starch indicator. The reaction is shown in the following equation:. The presence of the starch indicator gives an excess of thiosulfate. The iodine is completely consumed and the starch indicator becomes colorless.
This means that if the amount of thiosulfate added is known, the amount of copper present can be determined. To start off, 0. The solution was heated until the copper dissolved completely. This took roughly hours. After the copper had dissolved, the solution was cooled and diluted with 25 mL of deionized what are pre 1983 pennies made of. This step was necessary to eliminate nitrogen oxides which can come from the nitric aid, which catalyzes the oxidation of iodine.
This step is to help increase our yield of our copper content. The solution was cooled xre neutralized with 6 M ammonia until a blue-green precipitate had appeared. This is an important step because it helps assure the solution is not too acidic making the what tires fit 16x7 rims ions undergo an air oxidation and the results for percentage of copper will be lower than the actual content.
The pH of the solution was measured using pH paper. This step does allow for slight error, considering that some of the copper is removed when the pH do you know what that mean test is being performed. Next, 5 mL of glacial acetic acid was added to the solution to bring what does forza azzurri mean in italian pH to around 4.
This will what are pre 1983 pennies made of the precipitate. Then 3. The solution was then titrated with some sodium thiosulfate until the solution became a pale yellow color. Next, 5 mL of what are pre 1983 pennies made of starch indicator was added pee it change from yellow to purple.
The solution was further titrated until the solution became a dark gray purple. Finally, 2. The solution was stirred for approximately 30 seconds. During this time, the solution changed to a dark grey color.
Titration was performed until the solution was pale which means that the no iodine complexed with the starch indicator. After the weight was recorded, they were each placed in Erlenmeyer flasks. Approximately 25 mL of 6 M nitric acid was added to each flask and they were placed on hot plates to allow the pennies to dissolve. The flasks were cooled and 10 mL of sulfuric acid was added to each solution. The flasks wer reheated until white fumes of sulfur trioxide appeared. The flasks were removed from the heat and 6M ammonia solution was added until the copper hydroxide precipitate appeared.
The solution became blue and oof. The solutions were titrated as previously what animals are in the phylum mollusca with the only difference being the pre pennies.
Because of the high amount of copper found in these pennies, the solution was diluted in a mL and a 25 mL sample was diluted to use for titration. Copper percentage changed in pennies in The analysis of copper percentage of both pre and post pennies was analyzed using prnnies titration and the results of all students was compared.
The experimental values can be compared to the assumed values and error can be discussed. The results of all of the students can be compared to analyze for possible sources of errors.
The titration against pure copper standard allows for the determination of the molarity of the sodium thiosulfate solution.
This is shown in the following equation:. Each of the students performed the calculations based on their experimental data. The average value of the concentration of the standard sodium thiosulfate is 0.
The standard deviation was determined by taking each value of interest and subtracting the mean from it and then squaring that number. The number off is wgat divided by the degrees of freedom and then taking the square root of that number. The confidence interval is the standard deviation is multiplied by the t value.
What are pre 1983 pennies made of t value was obtained by a previously established chart showing the following calculation:. My results were within acceptable limits to the department of treasure results. There were many source of error in this experiment. The major contributor was the systematic user error. Because an exact endpoint could not be precisely measured due to the difficulty in the color change, some error was introduced in this experiment.
Some samples may have been too heated or left for additional minutes than required. Another source of error is the measuring of the pH of the solution after dissolving the pennies. Each time the pH is read, a small amount of copper is lossed giving a lower value for the pennies. Prw Documents. The Determination of Copper in Pennies.
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Pennies are commonly thought to be primarily Copper due to their distinctive color and for most of our nationТs history, that was true. However, contemporary pennies are zinc discs with a thin Copper shell. This composition became the standard in There were periods in our nationТs history when pennies were produced of other materials, such as during World War II when steel cents were used. partpresent Ц % zinc, % copper (Copper plated: Inclusive of bicentennial cent and Union Shield cent).** *the exception Ц pure steel, zinc-coated with rare error copper minted pennies. **exception Ц rare error copper minted pennies. The composition materials in pennies are primarily zinc. Oct 09, †Ј In and before, pennies were actually made primarily of copper instead of just being coated with it.
There are several ways to tell if your penny is zinc or copper. First and most easily, if your penny is dated or later, it is zinc. For pennies dated , it could be either zinc or copper. The simplest way to tell without using machinery is to weigh your penny with a scale that reads to the tenth of a gram.
A copper penny weighs 3. Though keep in mind, circulated coins do gather dirt, corrosion, etc. So the weight could be slightly off for individual coins. In general, if your penny is dated to with the exception of , you can rest assured your penny is a copper penny.
The U. If your penny is dated earlier than , it is copper. In , copper was heavily in demand to be used in war materials for World War II. Because of this, the penny was made of steel. There was a small amount of error pennies minted of copper in If you have a copper penny or copper penny , that could potentially be a rare and valuable find! We sort pennies into zinc pennies or copper pennies so that way you can buy copper pennies or buy zinc pennies efficiently and easily.
Learn about Copper Pennies. Hit enter to search or ESC to close. Zinc Penny or Copper Penny How to tell if your penny is copper There are several ways to tell if your penny is zinc or copper. There are rare exceptions to the above for telling if your penny is zinc or copper. X Close. We're here to help you! End chat. None of our operators are available at the moment.
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