Copper to Copper
Hayriye Polik
Asna Ashfaq and Isabella Stubbs
AP Chemistry 3rd Period
Dr. Kerr
08/28/2014
Purpose:
The purpose of this lab is to see how copper can be reacted with multiple substances and then
reversed back to copper in the end.
Materials:
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5.5 mL Concentrated Nitric Acid
Distilled Water
30 mL of 3 M NaOH
0.5 g Copper Turnings
15 mL 6 M H2SO4
Zinc Powder
250 mL beaker
Heat Plate
Stirring Rod
Filter Paper
Erlenmeyer Flask
Acetone
Procedure:
1. Reaction 1
a. Measure 0.5 g copper turnings into 250 mL beaker. Add 5.5 mL concentrated
nitric acid in the fume hood.
b. Add 75 - 100 mL distilled water after reaction is complete.
2. Reaction 2
a. Add 30 mL of 3 M NaOH to the solution above.
3. Reaction 3
a. Carefully heat the beaker containing Cu(OH)2 solid (frothing is normal) until
contents are totally black. Don't overheat.
b. Allow the black precipitate to settle. Decant. wash the precipitate with warm
water and decant to isolate black precipitate.
4. Reaction 4
a. Slowly add 15 mL of 6 M H2SO4 to the black solid. Stir.
5. Reaction 5
a. Add 2 g of zinc powder to the solution. All the zinc should be gone from the
reaction container at the end of the reaction. If not, add additional H2SO4. If all the
Cu2+ ions are not gone, add more zinc.
b. When the reaction is complete, filter. Wash the solid copper with water then
acetone. Let the solid copper dry. Weigh the copper and filter paper and calculate
percent recovery. If a white precipitate forms, add some warm water and stir.
Results:
Measurements and Data:
Mass of Copper Turnings
Mass of Filter Paper and
Dried Copper
Mass of Filter Paper
Mass of Dried Copper
Percent Recovery
0.5 g
1.32 g
0.89 g
0.43 g
90 %
Reactions and Observations:
Reaction
Type of
Reaction
OxidationReduction
Formula
Qualitative Observations
Cu(s) + 4HNO3 -> Cu(NO3)2 (aq)
+ 2NO2 (g) + 2H2O (l)
2
Precipitation
Cu(NO3)2 (aq) + 2NaOH (aq) ->
Cu(OH)2 (aq) + 2NaNO3 (aq)
3
Decomposition
Cu(OH)2 (aq) -> CuO (aq) +
H(OH) (l)
4
Precipitation
CuO (aq) + H2SO4 (aq) -> CuSO4
(aq) + H(OH) (l)
5
Single
Replacement
CuSO4 (aq) + Zn (s) -> ZnSO4 (aq)
+ Cu (s)
Copper turnings and nitric acid
turned green and released
brown/yellow gas. Solution
slowly turned blue. Upon adding
water, substance turned aqua
blue.
Solution clouded up and turned
cobalt blue. Jelly-like precipitate
formed.
While heating beaker with
Cu(OH)2, jelly-like substance
turned liquid. It became darker
over time, first turning dark green
then black. Black particles started
forming; this was the black
precipitate.
Upon adding 6 M H2SO4,
precipitate turned light brown and
homogeneous; became clearer
and green. With more stirring the
solution turned light blue.
As stirring continued, the zinc
powder turned reddish orange
(the copper). It clumped and
became solid. This was the
copper.
1
Analysis:
1.32 g (Mass of filter paper and Cu) - 0.89 g (Mass of filter paper) = 0.43 g (mass of Cu)
0.43 g Cu (ending result) / 0.5 g Cu (initial value) = 0.86(100) = 86% (need only one significant
figure because of 0.5 g, so the percent rounds up to 90%)
= 90% recovery of Copper
Conclusion:
In all, a range of chemical reactions were used to manipulate copper to reverse back into its
elemental form. Even though the coils weren't produced in the end, the pure copper was
produced, which was the main idea of the lab. There was a source of error because only 90% of
the copper was recovered. One source could be from human mistake in inaccurate measurements
of substances. A clear source of error occurred with decanting, because the black particles were
very challenging to keep from spilling into the sink. Another source of error could be while
stirring the Zinc powder with the solution: there wasn't enough time to make sure that all of the
zinc ions reacted with the Copper (II) Sulfate, which was the light blue solution. Being short on
time affected how the procedures were performed hurriedly and quickly. In conclusion, most of
the Copper was recovered through four different types of chemical equations.