Copper Cycle Lab
Introduction:
Have you ever noticed how many different uses copper has? The first things that come to mind
are probably coins and electrical wires. How many others can you think of? Why is copper so useful?
Copper is widely distributed in the Earth's crust. It is commonly found in sulfides, carbonates,
and as uncombined metal. It is a relatively soft metal, reddish in color, and similar in many ways to
another metal in Group 11, silver. It is an excellent conductor of electricity and heat, second only to
silver. Like silver, it maintains its integrity through a series of chemical reactions and has the advantage
of being relatively inexpensive.
In this investigation, you will perform a series of chemical reactions involving copper and copper
compounds. The equations for the reactions are listed here in unbalanced form.
Cu + HNO3  Cu(NO3)2 + NO2 + H2O
Cu(NO3)2 + NaOH  Cu(OH)2 + NaNO3
Cu(OH)2  CuO + H2O
CuO + H2SO4  CuSO4 + H2O
CuSO4 + Zn  Cu + ZnSO4
Beginning with a sample of copper of known mass, you will perform a series of reactions,
eventually recovering the copper at the end. You will then analyze your quantitative data to see what
percentage of the copper was recovered.
Materials:
250-mL Beaker
copper wire (22 gauge)
50-mL graduated cylinder
6.0 M HNO3 600-mL Beaker
ice
stirring rod
6.0 M NaOH
goldenrod paper
ring stand
iron ring
wire gauze
Bunsen burner
3.0 M H2SO4
zinc
evaporating dish
methanol
acetone
Safety:
Acids and bases are corrosive to the skin. If there is an accident rinse any contaminated area of your
body with plenty of water and notify your instructor immediately.
Procedure:
Part A (15 minutes)
1. Cut a 1 meter length of copper wire, and record the mass in your data table. Coil the wire into a flat
spiral, and place it in the bottom of a 250-mL beaker. Label the beaker with your name and lab
station.
2. Slowly add 25 mL of 6.0 M nitric acid to the beaker and then leave it in the fume hood over-night.
Record your observations.
Get
Here
On
Day 2
Part B (2 hours)
3. Put some ice and water into a 600-mL beaker until the beaker is about half full. Place the smaller
beaker in the ice bath to keep the reaction mixture cool.
4. Obtain 25 mL of 6.0 M sodium hydroxide in a graduated cylinder. While stirring, slowly add the NaOH
solution to the 250-mL beaker until the reaction mixture becomes basic. (To test the alkalinity of the
solution, use a stirring rod to place a drop of the reaction mixture on a piece of goldenrod paper.
Goldenrod paper turns blue in an acid and red in a base.)
5. To the reaction mixture from step 4, add 50 mL of water. Gently heat the mixture until it just begins to
a boil. Stir while heating for approximately 5 minutes. Remove the beaker from the heat using
beaker tongs and allow the solution to cool for approximately 5 minutes.
6. Decant the liquid from the beaker into the sink with the water running. While stirring, add 50 mL of
water to the precipitate in the beaker, let it settle, and decant the liquid. Repeat this process. It is
important that the precipitate remain in the beaker.
Add as
little Zn
as
possible
7. To the precipitate from Step 6, slowly add 50 mL of 3.0 M sulfuric acid while stirring.
8. Weigh out 10 grams of zinc powder. Slowly add the zinc (a couple grams at a time) to the solution
from Step 7 while stirring, until all of the blue color disappears from the solution. You may not need
all 10 grams of the zinc to accomplish this.
9. Since there will be excess zinc remaining in the beaker, add 30 mL of 3.0 M H 2SO4 and stir. The
bubbles indicate the evolution of hydrogen gas from the reaction mixture. Place the reaction mixture
in the fume hood and let the mixture continue to react until the next class period.
Part C (1 hour)
10. Add an additional 20 mL of H2SO4 and check to see that all of the zinc has reacted. When there is no
visual sign of any hydrogen gas bubbling, nor any silver colored metal at the bottom of the beaker,
decant the liquid.
11. Add 50 mL of water to the reaction mixture, stir, allow the copper to settle, and then decant the liquid.
Repeat this process 2 more times.
12. Pre-weigh an evaporating dish, and then transfer the solid to it. Rinse the copper with 5 mL of
methanol and decant. Rinse the copper with 5 mL of acetone and decant. Place the evaporating
dish in the drying oven and evaporate the remaining liquid from the copper precipitate. Remove the
evaporating dish from the drying oven and let it cool.
13. Find the combined mass of the copper and the evaporating dish and record it in your data table.
14. Dispose of the recovered copper as directed by your teacher. Clean up your work area and wash
your hands before leaving the laboratory.
Data Table:
Record your qualitative and quantitative observations as you perform the experiment in the following
style.
1
2
10:30 AM -- Copper wire weighed 2.07 grams.
10:45 AM -- Added 25.0 mL of 6.0 M HNO3 to the copper wire.
Reaction bubbled, reddish-brown gas was given off, solution turned a clear blue, copper
wire disappeared.
Calculations:
1. Calculate the percent yield of the experiment by dividing the mass of copper recovered from the
experiment by the original mass of copper, and then multiplying by 100%. (As always, show your
work.)
Analysis and Conclusion Questions:
1. Write out and balance the 5 reactions involving copper in this experiment. (Include states of matter.)
2. What reactions were metathesis/double replacement reaction reactions in the lab?
3. What reactions were oxidation reduction reactions in the lab? What is/are the oxidizing agent, what
is/are the reducing agent, balance them as if they are in an acidic solution.
4. What is the difference between metathesis and oxidation reduction reactions?
5. Was the first reaction endothermic or exothermic? Explain your response.
6. When sulfuric acid and copper(II) oxide are reacted copper(II) sulfate and water are formed, write a
balanced chemical reaction for this process.
7. What is the purpose of adding water and decanting in step #11?
8. What should the maximum percent yield be for any reaction?
9. Describe each of the steps during the experimental procedure where you might have lost some
copper. Which one of these steps do you think was the most significant? Why?
10. What impurities might there be in the final product? How would the presence of impurities effect the
percent yield calculation?
11. How efficient were you at recovering your initial amount of copper? (Discuss the meaning of your
percent yield.)
Teacher Prep Information
6.0 M Nitric Acid
25 mL per group – for 32 groups/2 classes need total of 800 mL
M1V1 = M2V2
15.7 M V1 = 6.0 x 1.00 L
V1 = 0.382 L of HNO3 and 0.618 L of water
Concentrated HNO3 is 15.7 M, take 382 mL of acid and mix with 618 mL of water
(for two classes).
6.0 M NaOH
25 mL per group – for 32 groups/2 classes need total of 800 mL
6.0 mole NaOH
1.0 L NaOH
1 L NaOH
1000 mL NaOH
40.00 g NaOH
1.00 mole NaOH
= 240 grams of NaOH in 1000 mL of water
6 M NaOH, take 240 grams of NaOH pellets and combine with 1000 mL of water
(for two classes)
3.0 M Sulfuric Acid
100 mL per group – for 32 groups/2 classes need total of 3200 mL
M1V1 = M2V2
18.0 M V1 = 3.0 x 4.00 L
V1 = 0.667 L of HNO3 and 3.33 L of water
3.0 M H2SO4, take 333.5 mL of concentrated H2SO4 and combine with 1665 mL
of water (for two classes). DO THIS TWICE