Lab Report Write Up (30 Points)
Name: Loren Fuller and Briana Jackson
Title: Chemical Reactions of Copper and Percent yield
Purpose: The purpose of this experiment was to help us as new scientist to gain familiarity with basic
laboratory procedures, chemistry of a typical transition element, and the concept of percent yield.
Procedure and Modifications:
A. Weigh 0.500 grams of copper wire and then place it in a 250-mL beaker. Then add, 4-5mL of
concentrated HNO3 to the beaker. After the reaction is complete, add 100mL of distilled H20,
Litmus paper was then used to test how basic the solution was.
B. We were then asked to describe the reaction per the color change, evolution of gas, and change in
temperature (exothermic or endothermic). We then added 30mL of 3.0 M NaOH to the solution in
your beaker and describe the reaction. Add three boiling chips and carefully heat the solution using
a Brunson burner, while stirring a with a stirring rod-only to the boiling point.
C. We allowed the black CuO to settle; then decant the supernatant liquid. Then added about 200mL
of very hot distilled water, stir, and then allow the CuO to settle, then decant once more. After we
added 15mL of 6.0 M H2SO4.
D. Reduction with Zinc: Add 2.0g of 30-mesh zinc metal all at once to the above acidic solution and stir
until the supernatant liquid is colorless. When gas evolution has become very slow, heat the solution
gently, and allow it to cool.
E. Reduction with Aluminum: We did not use aluminum sheets instead we used zinc to show the
reduction process.
F. When the gas has ceased, decant the solution, and transfer the precipitate to a pre-weighed weighing
dish (we did not use porcelain). We washed the precipitated copper with about 5mL of distilled
water, allowed it to settle, decant the solution, and repeated the process till the Zinc Sulfate was
separated from the solution.
G. Finally, we washed the precipitate with about 5mL of methanol, allowed the precipitate to settle, and
decant the methanol. After, we washed the precipitate with about 5mL of acetone, allowed it to
settle, and decant the acetone from the precipitate. We then prepared a steam bath and dried the
product on the steam bath at least 5 minutes. We removed the boiling chips and weighed the
evaporating dish plus the copper. We calculated the final weight of copper, compared it to the initial
weight, and calculated the percent yield.
Observations: After adding 4-5mL of HNO3 to the .5 grams of copper, we noticed a dark
orange/brown fume of nitrogen oxide emitting from the beaker which was an exothermic
reaction. After the fume dissipated, we were left a bright green aqueous solution of copper
nitrate; when tested for ph blue lithmus paper, it turned red indicating an acidic solution.
When adding 30mL of sodium hydroxide to copper nitrate, the solution turned dark blue
almost black, we tested the ph with red lithmus paper and found it had turned blue indicating a
basic solution. The experiment instructed to wash the solution of the precipitate, so we boiled
the solution, to our surprise after hitting a certain temperature past water’s boiling point and
constantly stirring, the solution turned jet black. As the solution cools, the mixture begins to
separate into a black solid which was the precipitate (Sodium Nitrate) and water. We added
15mL of 6.OM H2SO4 (Sulfuric Acid), which turned the solution from a jet black solid in an
aqueous solution to a clear, sea blue with no black substances left in the beaker called copper(ll)
sulfate. We then added 2.0g of zinc metal, immediately causing a reaction; the solution started
to bubble, and heat up extremely fast, once the water vapor emitted had dissipated, a red-
copper colored solid substance was left in the beaker. We then had to wash/decantate the
solution using using 5 mL of distilled water, methanol and acetone separately using the
instructions stated earlier, to remove the zinc sulfate leaving only copper left in the beaker, as
we had previously started with. We prepared a steam bath and let the product which was like
red, sedimentary dry, and removed the boiling chips.
Results: (Include Report sheet)
Error Analysis:
During the experiment, one of the procedures required for the drying of the copper collected. Initially
our group was told that we did not allow for the copper to completely dry, affecting our weight
calculation. What we did to correct this error was place the weighing dish containing the copper back
onto the boiling water until it was completely dry. Another place where analysis possibly occurred is
when weighing to see how much copper remained after the entire experiment. We recognized that we
did not remove all of the boiling chips which could have affected our mass of copper. The incorrect
mass would have then affected our mass percentage.
Conclusion:
After conducting the entire experiment, there are a couple of takeaways. First, we gained more
experience with using a balance, graduated cylinders, beakers, hot plates, and other lab materials. We
also were able to observe chemical reactions happen. These reactions include two redox reactions , 2
metathesis reactions, and a dehydration reaction. One example is when one of our solutions turned
entirely blue. That was a metathesis reaction between Cu(NO3)2 (copper nitrate) and NaOH (sodium
hydroxide). Lastly, we learned how to apply our knowledge of calculating mass percent and how
important getting exact data is for getting correct calculations. We recognized this during the final
weighing of copper when we saw that there was excess material (boiling chips) in the copper.
