Determination of % Composition of Pennies Using Spectroscopy Essay

The Congress authorized the amount of copper in a penny after 1982 to be 2.5% by mass. The mean value found from this lab was 3.018%. There were no discernable variations based off of the penny’s apperance or mint date. The value reached from this lab is significantly different from the authorized copper content.

3. Find the number of atoms of each of the substances involved in the reaction.

10. As described in problem 7, a procedure was developed to determine the percent zinc in post 1982 pennies. In that procedure 50 ml of an HCl was used to react (dissolve) all of the zinc in the penny. To ensure complete reaction, the solution contains twice as many moles of HCl that is actually needed. To determine the percent zinc in the penny, the excess (unreacted) HCl was titrated with NaOH. Determine the concentration of NaOH needed if you want to use approximately 25 mL of NaOH to titrate the excess HCl.

The first question in the problem read: In caring for a patient after delivery, you are to give 0.2 mg Ergotrate Maleate. The ampule is labeled 1/300 grain/ml. How much would you draw and give? (60 mg = 1 grain). In reading this problem, the information that I need is given: I need to draw and give 0.2 mg of a certain medication. Also given is that 60 mg is equal to 1 grain. Another important piece of information is that there is 1/300 grain per 1 ml of solution, without this information, the problem would be unsolvable. The process that I

In your laboratory notebook sum these two reactions to find the stoichiometric factor that relates moles of

c. A lab exercise in BIO156 required 300 ml of water that was poured from a two-liter container. How many milliliters were left in the original container? (4 points)

The purpose of this experiment was to find, compare, and contrast the mass, volume, and densities of copper and zinc pennies. Information about the pennies was acquired before the start of the lab. The pre-lab research stated that any pennies that were minted before 1982 are composed of pure copper, while any pennies after 1982 are made out of zinc. The densities of copper -- 8.96 grams per centimeters cubed -- and zinc -- 7.13 grams per centimeters cubed -- were also information that was acquired before starting the experiment. With knowing the density of the two metals, this hypothesis was formed: If the mass and volume of pennies made out of zinc and copper are both measured, then the copper pennies will have a greater mass, because copper has a greater density than zinc. This hypothesis was formed because density equals mass over volume and if the mass is greater in an object that has the same volume, then the density of the object will be greater than the other.

XIV. Record your observations of the dried, cooled copper metal and weigh the recovered copper.

5. When 11.2 liters of hydrogen gas is made by adding zinc to sulfuric acid, what mass of zinc is needed?

This experiment was performed to become familiar with chemical formulas and the processes for the chemical reactions. By breaking down the chemicals, we were able to obtain certain reactants that were already part of the product. In three trials, the zinc chloride’s mass ranged from 1.16 g to 1.62 g. Mass of the chlorine found in the zinc chloride ranged from 0.66 g to 0.96 g. In the three trials of the copper sulfide lab, the copper sulfide’s mass ranged from 2.38 g to 3.18 g. The mass of the sulfur in this lab ranged from 0.64 g to 1.51g.

H. In order to prepare 10 mL of 0.25 M HCl solution, you need dilute 2.5 mL of 1M HCl to 10 mL by adding (10 mL - 2.5

First, the lead cylinder and the zinc cylinder were weighted and their masses were found. Then 15.0ml of water was added

How much sodium chloride can be formed with sodium carbonate and hydrochloric acid? The law of conservation of mass is being and the law of definite proportions is being used. Sodium Chloride will be the result of the reaction between two compounds. The expected result for the product was for it to be around 1 gram. After finding the theoretical yield it was expected to be something less than the theoretical yield. The independent variable would be the boiling of the water while the dependent is the Sodium chloride.

The determination of the amount of copper in a penny involves multiple scientific concepts that are extremely important. First, the experiment involves a redox reaction of Copper and Zinc. Copper and zinc are both components of a penny and the oxidation reaction utilizes nitric acid, a very strong oxidizing agent, in order to oxidize both copper and zinc. The reaction generates a highly toxic, brown gas which is nitrogen dioxide (NO2), but more importantly, it results in the complex ions of copper and zinc. The complex ion generated of copper is Cu(H2O)42+ and has a dark blue hue while the complex ion generated of zinc is Zn(H2O)42+ and does not have a distinctive color. Essentially, a complex ion is formed by having a central metal ion that has formed covalent bonds with multiple ligands, which are simply anions. Furthermore, the Beer-Lambert Law establishes a relationship between light absorption and solution concentration by claiming that the concentration of a certain solution is directly proportionate to the total amount of light energy that the compound present in the solution can absorb (The Beer-Lambert). A spectrophotometer can be utilized to measure how much light energy of a certain chosen wavelength is absorbed by a particular sample.

Using the equation of the reaction for the HCl titration and the calculation from your practical books; calculate the exact concentration of the sodium hydroxide used. Show your calculation