Name__________________________________________________ Date_______________ Period___
Chemical Reactions in a Copper Recycling Process
Purpose and Rationale: The purpose of this experiment is to observe a display of chemical changes and to
write balanced equations for the reactions that occur. In this experiment, metallic copper is taken through a
variety of chemical changes that eventually lead to the recovery of the copper metal. This will reaffirm
fundamental laws such as the constant composition of matter and the law of conservation of mass, as well as
illustrating an industrial recycling process.
Materials and Methods:
Materials: Normal laboratory apparatus 6M nitric acid solution 6M sodium hydroxide solution Cu metal
3M sulfuric acid solution #20-mesh Zn metal
Methods: Since “industrial strength” corrosive acids and bases are used in this experiment, safety goggles
and aprons will be worn at all times during all phases of the experiment. The “M” numbers refer to the
concentration of the acid or base. The higher the “M” number, the more concentrated the acid or base.
Day 1: Conversion 1 – Changing copper metal to copper (II) nitrate
Place approximately 1.5 grams, massed to 0.01g, of copper metal into a clean 250ml beaker. Make sure that
your initials and class period are on a small piece of masking tape up near the rim of the beaker. In the fume
hood, your teacher will carefully add about 30ml of the nitric acid solution to one of the preparations so you can
make observations (because a poisonous gas is produced, your teacher will add the nitric acid to the rest of the
preparations after school and let the digestion proceed overnight so you will not be exposed to the poisonous
gas).
We will leave the beakers in the hood overnight. The reaction starts slowly, but if you come back after
5 minutes or so you should be able to see the poisonous nitrogen dioxide gas coming off your reaction
mixture.
This reaction is:
solid copper + nitric acid solution  copper (II) nitrate solution + liquid water + nitrogen dioxide gas.
Write the balanced equation for this conversion in the space above. On a separate sheet of notebook
paper, record your careful observations and lab notes.
Day Two: Conversion 2- Changing copper (II) nitrate into copper (II) hydroxide
Bring your beaker to your lab workstation. Make a cooling bath: to a 600ml beaker, add enough cold
tap water to make it about 1/3 full. Nest your labeled beaker into the larger one. The cold tap water in
the larger beaker will help cool the next reaction, which is “exothermic” (gives off heat).
Slowly (CAUTION) while stirring with a glass rod, add (slowly!) 30ml of sodium hydroxide solution.
This solution neutralizes the leftover acid from conversion 1 but has the potential of producing
considerable heat.
Using your stirring rod, place a drop of this solution (try to get the clear part instead of the blue
precipitate) on a piece of red litmus paper. It should turn blue. If it does not, add 5ml of sodium
hydroxide solution, stir and test again. Make sure the red litmus paper turns blue.
This reaction is:
copper (II) nitrate solution + sodium hydroxide solution  sodium nitrate solution + copper (II)
hydroxide(s)
Write the balanced equation for this conversion in the space above. On a separate sheet of notebook
paper, record your careful observations and lab notes.
Day 2: Conversion 3- Changing copper (II) hydroxide to copper (II) oxide
Remove your 250ml beaker from the 600ml cooling beaker. Rinse the large beaker and put it away.
To your labeled beaker add about 100ml of deionized water. Set up a heating / stirring hot plate and
get ready to heat your labeled beaker. Caution ! Carefully and slowly heat the mixture from
conversion 2. Record observations. If you heat it too strongly, especially without stirring, the beaker
may actually “bump” off the hot plate and splash hot chemicals all over as it breaks on the lab bench.
So, now stir the contents without splashing and heat until it turns completely black. Place the beaker in
your class period’s “parking area” to let the precipitate settle overnight. Caution ! The beaker tongs
may let the beaker slip through them if you do not grip the beaker firmly.
Day 3: Conversion 3, continuedCarefully retrieve your beaker from your class period’s “parking area”. Be careful not to stir up the
separated mixture as you are walking to your lab bench. At your lab station, decant off the clear liquid
with the help of a clean glass stirring rod and a disposable ungraduated Beral pipet.
Add about 150ml of deionized water, stir, let the precipitate settle and decant again. You do not have
to remove every last little bit of water but be patient on this part. Repeat this procedure with another
150ml of deionized water. Be sure you have “washed the precipitate” at least three times (four is mo’
betta’) with deionized water or the next step may produce poisonous nitrogen dioxide gas.
Write the balanced equation for this reaction in the space below. On a separate sheet of notebook
paper, record your careful observations and lab notes.
The reaction for conversion 3 is:
copper (II) hydroxide(s)  copper (II) oxide(s) + liquid water
Day 3: Conversion 4- Changing copper (II) oxide to copper (II) sulfate
To the washed copper (II) oxide in the beaker carefully add about 50ml of 3 M sulfuric acid. The “3
M” refers to the concentration of the acid. Stir gently. Wash off the glass stirring rod before placing it
on the lab bench. Do you know why?
This reaction is:
copper (II) oxide(s) + sulfuric acid solution  copper (II) sulfate solution + liquid water
Write the balanced equation for this conversion in the space above. On a separate sheet of notebook
paper, record your careful observations and lab notes.
Day 3: Conversion 5- Changing copper (II) sulfate solution to solid copper
Mass about 6 grams of #20-mesh zinc into a small plastic condiment cup. Bring your beaker and zinc
to the fume hood. Pour the zinc into the beaker all at once. Do not breathe the irritating spray coming
out. Record observations. There are two chemical reactions occurring. The first one below shows the
change with the copper (II) sulfate solution. The second one shows the reaction of the zinc with the
acid.
Reaction 1: copper (II) sulfate solution + solid zinc  zinc sulfate solution + solid copper
Write a balanced equation for this reaction in the space above.
Reaction 2: solid zinc + sulfuric acid solution  zinc sulfate solution + hydrogen gas
Write the balanced equation for this reaction in the space above. On a separate sheet of notebook
paper, record your careful observations and lab notes.
When you are sure that the reaction is complete, decant off the liquid that is on top of your product of
recovered solid copper. Wash twice with about 200ml of deionized water to remove most of the
aqueous zinc sulfate. Filter the solid into a massed piece of filter paper. Remove the filter paper with
the solid and place it into your labeled beaker to dry. Clean your lab area.
Day 4: Results and Discussion
Remass the filter paper containing your dry solid and record. Remove the label on your beaker, wash
twice with soap and water, and rinse well with tap water and then twice with deionized water and put it
away. Be sure all glassware is cleaned and put away, all apparatus is disassembled and put away, and
your lab area is sponged off. Hope this was fun! Also, compute a percent recovery in the space below.
(recovered mass of solid copper / initial mass of solid copper)(100) = % recovery
Don’t worry if your % recovery is not 100%, but give some reasons why you think it is what it is.
On the back of this sheet, discuss each reaction in this lab. Students who avoid this may be
disappointed in their lab grade, while students who include extensive discussions should be well
satisfied with their lab grade.