Research Question: What is the percent composition of Copper and Zinc in a positive penny? Aim: The purpose is to determine the percent composition of Zinc and Copper metals in a post-1983 penny with the use of HCI. Variables: Independent Variable: percent composition of Zinc. Dependent Variable: percent composition of Copper. Controlled Variable: Military of HCI, and year tot penny. Apparatus: Beaker Goggles penny Distilled Water Method: Note that HCI is an acid and must be cautious around this acid for it can burn your eyes so wear goggles, and wash hands after the lab.
I. Retrieve a penny that is post 1983, and clean and dry the beaker you are going to use to make sure it has no residue from any previous users. 2. Fill 3 slots into a copper about 1/3 of the way or till you see the gray portion. (Note it will be more effective if each filling mark is at 1200 angle Of each Other. ) 3. Once the penny has been filed, weigh it and record its mass. 4. Weight the beaker and record it’s mass, then add penny in the beaker and mass or you can indirectly measure the mass by adding the penny mass with the beaker mass. 5.
Place the penny in the beaker and add the HCI. Let sit for a day and recover your penny. 6. After the penny seems hollow retrieve the copper shell and mass it. 7, Once massed use the percent composition formula to find out how much copper is in a penny. (Percent composition formula: % comb= partial mystical mass x 100) 8, Subtract your finding of the percent composition of copper from 100 to find percent composition of zinc, 9. Repeat steps for multiple trials. Data: Date of penny: 1984 Mass of Beaker: 29. Gag Mass of penny: 2_gag Mass of beaker + penny: 32. 1 Mass of copper residue: Alga % comb Copper: 35% . Gag. gag x 100 = cue % comb. Zen-65% Pre Mass (g)l Post Mass (g) I % composition Cue % composition Zen 1 2. Gag o_gag | | 2. Gag 0. Gag 130% | 2. Gag 0. Gag | 2. Gag 0. Gag | | Average Mass of copper- Bag. Cue Conclusion: At the end of the experiment, through the use of percent composition, the copper within the post-1983 penny was found to be 35 percent, and 65 percent zinc. Some sources of error were filing the penne’s sides to open it up for the reaction, The only solution to the problem is keep filing the.
Human error was he largest source tot error in the lab. Finding the mass tot two objects and using indirect measurements could lead you to the wrong number depending on rounding, thus slightly increasing or decreasing your percent yield in the experiment. Also if you use the wrong sit figs while solving for the percent composition this could cause problems. If were to retry lab, would make sure to file more than what thought was needed, and to make sure to get a penny of the same year for a second trial. By adding a catalyst, a change in the speed of the reaction could reduce the time needed.