Name______________________
AP Chemistry
The Copper Cycle
Purpose- to gain familiarity with basic laboratory procedures, some chemistry of a typical transition
element, and the concept of percent yield
Materials- Copper wire ,Balance, 2 250mL, distilled water, evaporating dish, stirring rod, wire guaze,
ring stand and iron ring, Bunsen Burner and hose, 100mL graduated cylinder, boiling chips, hot plate
Chemicals- 0.5g of Cu, 6M H2SO4, Acetone, aluminum foil, Conc. HNO3, 3.0M NaOH, Conc. HCl
Procedure1. Weigh approximately 0.50g of Cu wire and record on your data table.
2. Place copper in a clean 250mL beaker and label your beaker. Place the beaker in the fume hood.
3. Add 5.0mL of Concentrated Nitric Acid HNO3 to the beaker and record observations.
***CAUTION If Nitric Acid gets on you it must be washed off immediately with copious amounts of
water. ***This reaction must take place in the fume hood due to the production of toxic gas.
4. After the reaction is complete (no copper remains), add 100mL of distilled water to the beaker.
5. Add 30mL of 3.0M NaOH to the beaker (record observation).
6. Take a stirring rod a drip a drop of the solution onto red litmus paper. If it stays red add 10 more mL
of NaOH to the solution until the drop turns the litmus paper turns blue.
7. Add 2 boiling chips provided by your instructor to the solution, then heat the solution on the hot
plate, while stirring. When all the precipitate has changed color remove the beaker from the heat.
Record Observation.
8.Allow the solid to settle, then decant the supernatant. Careful not to lose any solid.
9. Add 100mL of distilled water and decant once more.
10. Carefully remove the boiling chips. Rinse any of the solid back into the beaker and dispose of the
boiling chip.
11. Add 50mL of distilled water. Then add 15mL of 6M H2SO4 to the beaker and stir until all the solid has
reacted. ***CAUTION If H2SO4 gets on you it must be washed off immediately with copious amounts of
water. Record Observation.
12. Mass approximately 0.30g of Al. Shred them and place in the solution. Place the beaker in the fume
hood and add a few drops of Conc. HCl (12M) to the beaker. ***CAUTION If HCl gets on you it must be
washed off immediately with copious amounts of water. Record Observation.
13. If the solution is still blue, add a few more squares of aluminum. If aluminum remains add, a few
more drops of HCl, until no Aluminum remains.
14. Decant the supernatant from the copper.
15. Mass a clean, dry evaporating dish and record the mass in the data table.
16. Using an inverted water bottle, rinse the copper into the evaporating dish.
17. Decant the water from the copper.
18. Add a few drops of acetone to the copper and allow to air dry for a few minutes.
19. Mass the evaporating dish and copper. Record on data table.
Prelab Questions1. If a % yield is greater than 100%, what are 2 plausible errors you may have made in an experiment?
2. Consider the combustion of methane CH4
a. Write the balanced chemical equation
b. If 2 moles of CH4 and 3 moles of O2 are reacted, which is limiting?
c. How many moles of CO2 are produced? How many grams?
3. Define molarity.
4 Complete the reaction and balance
H2SO4 + CuO -->
5.How many mL of 6.0M H2SO4 are required to completely react with 0.80g of CuO?
6. Complete the reaction
Al + CuSO4 -->
If 2.00g of Al metal reacts with 1.75g of CuSO4, how many grams of Zn remain?
Data, Observations and Calculation
1. initial mass of copper wire used
_________________g
2. Final mass of copper and evaporating dish
_________________g
3. Mass of evaporating dish
_________________g
4. Mass of recovered copper
_________________g
5.Percent Yield
Complete the reactions and record observations
6. Cu(s) +HNO3(aq) ==>
7. Cu(NO3)2(aq) + NaOH(aq) ==>
8. Cu(OH)2(s) ==>
9. CuSO4(aq) + Al(s) ==>
Questions
1. Why did you have to test the pH of the solution before proceeding to step 7?
2. What ions are present in the solution that was decanted in step 8?
3. What is meant by the term decant?
4. List 3 sources of error in this experiment that you witnessed in this lab that would lower a groups
percent yield.
Conclusion-