# Essay On Penny Lab

444 Words2 Pages
The purpose of the lab is to acquire the percent composition of zinc and copper. The procedure included obtaining a post 1983 penny and washing it with soap and water. Using a triangular file, we made an X on the penny. Then, we cleaned the top and bottom of the penny with steel wool until it was shiny. We rinsed the penny in acetone and dried it with paper towel. Next, we determined the mass of the penny by placing it on a balance. The mass of the penny was 2.47 grams. Afterwards, we placed the penny in a beaker filled with 20 mL of 6 M HCl. In the end we put the beaker in the fume hood and allowed it to sit overnight. During day two of the penny lab, we removed the penny skin from the beaker using tweezers. We rinsed the penny skin with…show more content…
To calculate the percentage of Cu, we divided the final mass of the penny 0.09 and the initial mass of 2.47 and multiplied by 100. To calculate the percentage of Zn, we divided the final mass of the penny 2.38 and the initial mass of 2.47 and multiplied by 100. During the experiment the hydrochloric acid donated its hydrogen ions in the reaction and then the chloride ions reacted with the zinc ions in the solution. Thus, the zinc dissolved in the highly acidic solution which was caused by the high concentration of H2 ions. Hydrogen gas was generated during the reaction which was seen when bubbles were formed as the penny was dissolved into the beaker. An error that could have been present during the lab includes not letting the zinc react completely with the chloride ions by removing the penny too early from the solution. For instance, the percent error of this lab was 45.6%, which was determined by the subtraction of the theoretical percent of Cu 2.5% and the experimental percent of Cu 3.64% and dividing by the theoretical percent of Cu 2.5%. This experiment showed how reactants react with one another in a solution to drive a chemical reaction and the products that result from the