Name ________________________________________ Lab



Name: __________________________________ Block:_______

Percent Yield Lab

Purpose: In this lab you will run a reaction between solid iron and copper(II)sulfate. You will measure the amount of copper produced. Then, you will calculate the theoretical yield of copper and use these two values to determine your percent yield.

Pre-lab Questions

1. Write a balanced chemical equation for the reaction in this lab. Assume the iron in the product has a +2 charge

2. Define the following terms in your own words: limiting reactant, excess reactant and percent yield.

Procedure:

1. Measure out approximately 6 grams of copper (II) sulfate in a plastic weighing tray. Record the exact mass in your data table.

2. Add the copper (II) sulfate and approximately 50.0 mL of warm distilled water to a beaker (water is located in the fume hoof). Record your observations of what happens when the copper (II) sulfate is added to water.

3. Stir the copper (II) sulfate solution until all the crystals are dissolved.

4. Measure approximately 1.00 g of iron filings in a clean plastic tray. Record the exact mass of iron used in your data table.

5. While stirring with the glass-stirring rod, slowly add the iron to the copper (II) sulfate solution.

6. Allow the beaker to sit for about 10 minutes while the reaction progresses. Record your observations.

7. While you are waiting, write your names on a piece of filter paper, then find and record the exact mass of the filter paper.

8. Fold the piece of filter paper in quarters and fit it snugly in the funnel. Add a small amount of water from your wash bottle to help the paper stick to the sides of the funnel.

9. Filter the mixture into an Erlenmeyer flask.

10. Using the rubber policeman, stir the mixture vigorously. Then, pour the mixture into the funnel. Scrape all of the solid into the funnel using the rubber policeman. When all of the mixture has been poured into the funnel, use a small amount of water to rinse the beaker into the funnel. Using a small amount of water, rinse the solid in the funnel to be sure all of the solution has drained through. Record your observations of the solid on the filter paper and the liquid in the flask after filtering.

11. Carefully, remove the damp filter paper from the funnel and lay it flat on the lab bench. Allow the paper to dry overnight.

12. Clean all of the lab materials, your bench, and your hands. Dump all of the remaining liquid into the waste container in the hood. Do not pour it down the sink.

13. Day Two: Find and record the mass of the dried solid and the filter paper. Your dried product can be disposed of in the trash.

Analysis:

• Data Table: Based on the procedure, construct a data table to record all required measurements in the lab.

• Observations: Based on the procedure, construct an observations table to record all required qualitative observations.

Calculations:

1. Calculate the maximum number of grams of copper that could theoretically be produced. The molar mass of copper (II) sulfate is 249.7 g/mol. *Note the copper (II) sulfate you used was actually a hydrate. (Day 1)

2. Calculate the mass of copper actually produced (Day 2)

3. Calculate the percent yield using the actual and theoretical masses calculated above. (Day 2)

Conclusion: Provide a brief (3-4 sentences) summary of your results and how they relate to the scientific content being discussed in class.

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