Penny Lab

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Percent Composition of a Penny
Background Information: Post-1983 pennies have a copper jacket and a zinc core. We hope to determine the percent composition of these two metals. This will be done by reacting the zinc with hydrochloric acid to form zinc ions in a single replacement reaction. The acid reacts with the zinc but not copper. The reaction of zinc metal with the hydrochloric acid (HCl) produces zinc chloride and hydrogen gas. Safety: Wear your safety goggles and apron If you spill Hydrochloric acid on yourself, rinse with water Procedure: DAY I 1. Take a post-1983 penny and, using a triangular file, etch an “X” on one side of the penny. Also etch a notch on the edge of the penny in the four positions shown in the diagram. 2. Mass and record the mass of the penny. 3. Using a graduated cylinder, measure 60.0 mL of 3.0 M HCl and pour it into your 100mL beaker. 4. Place the penny in the HCl solution etch side up and record observations for 3-5 minutes. 5. Place the beaker in your lab drawer. 6. Answer question #1 for tomorrow. Read and prepare a data table for Day II. DAY II 1. Using your forceps, carefully remove the fragile copper jacket that is left from the penny. Rinse it gently in distilled water. 2. Dry the penny in acetone solution. Swirl the penny in the solution. 3. Pour the acid solution from your beaker into the waste container at the center table. Rinse and dry your beaker. 4. Take a magic marker and write your lab drawer number on the side of your 50 mL beaker. 5. Place the penny in the beaker and put the beaker on the appropriate shelf of the drying oven. DAY III 1. Mass and record the mass of the dry copper jacket. 2. Complete the questions and calculations for tomorrow.

Questions Answer in complete sentences SHOW ALL MATH FOR CREDIT! INCLUDE UNITS & SIG FIGS IN ALL ANSWERS! 1. Write the balanced equation for the reaction. Include (states). 2. Calculate the mass of zinc found in the penny. 3. Calculate the mass of copper in the penny. 4....
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