CHEMISTRY/EXPERIMENT
CHEMICAL REACTIONS OF COPPER
Elemental copper metal will be converted into Cu2+ ion and then brought through a series of compound conversions
until the copper is returned to its original form as a metal. The conversions will illustrate various types of chemical
reactions including single replacement reactions, double replacement reactions, neutralization reactions, oxidationreduction reactions, and decomposition reactions. The reactions will also demonstrate the evolution of a gas, the
generation of heat, and the formation of a precipitate. The purpose of this experiment is to observe each of the
conversions and then write balanced chemical equations for each reaction. By noting the nature of the changes, the
proper phase notation can be added to the equations. When the original mass of the copper is compared to mass of the
copper recovered, the Law of Conservation of Mass can be verified.
PROCEDURE: WEAR SAFETY GLASSES THROUGHOUT!
CONVERSION 1
1. Clean, dry, and label a 100 mL beaker. Determine its mass and record.
2. Obtain approximately 0.5 grams of copper turnings, place in the beaker and determine the mass of beaker plus
copper. Record on data table.
3. In a fume hood, carefully add 10 mL of 6M nitric acid (hydrogen nitrate) solution (CAUTION!) to the copper
using the graduations on the beaker. Do not inhale fumes. Place a watch glass on top of the beaker. Note the
nature of the two reactants and any products which form.
4. Leave in fume hood overnight.
* The word equation for the oxidation‐reduction reaction in Conversion I is: copper + nitric acid → copper(II) nitrate + nitrogen dioxide + water Write and balance the formula equation for this reaction in the analysis section. CONVERSION 2
5. Obtain your beaker and test the blue solution with pH paper as indicated by your instructor.
6. Obtain 10 mL of 6M sodium hydroxide (CAUTION!) solution in a 50 mL beaker using the graduations on the
beaker. Test the solution with pH paper as before.
7. Fill a 250 mL beaker 1/3 full of ice water. Carefully place the 100 mL beaker containing the Conversion I solution
inside the 250 mL beaker so the beaker floats in the water.
8. Add cautiously and slowly, the 10 mL of sodium hydroxide solution to the blue copper (II) nitrate solution in the
100 mL beaker. Stir gently with a glass stirring rod. Considerable heat is generated by this reaction.
9. Test the resulting solution with pH paper. If this pH test does not match the original color of the sodium hydroxide
solution, add additional sodium hydroxide solution, a little at a time, while mixing until it does. Note color of the
solid which forms. Rinse the 50 mL beaker with water.
* The reaction between the excess nitric acid(hydrogen nitrate) solution from Conversion I and the sodium hydroxide solution is an acid/base neutralization (double replacement) reaction. Complete the word equation for this reaction. Write and balance the formula equation for this reaction in the analysis section.
* The remaining sodium hydroxide solution reacts with the copper (II) nitrate in a double displacement reaction. The new copper compound is insoluble and forms a precipitate (solid). The other salt is soluble and remains in solution. Complete the word equation for this reaction. Write and balance the formula equation for this reaction in the analysis section. CONVERSION 3
10. Add distilled water to the beaker to the 60 mL mark. Heat on a hot plate to a gentle boil and stir until all the
material is converted to a black-brown substance. This substance is copper (II) oxide.
11. Remove the beaker from the hot plate, using beaker tongs, and let cool on an insulating pad for 5 minutes. This
wait will allow the black precipitate to settle. Pour off the clear liquid on the top into a 250 mL beaker. Try not to
lose any of the black solid.
12. To rinse the black solid, add 50 mL of distilled water to the beaker. Stir gently. Let the precipitate settle for
another 5 minutes and pour off the wash water into the same 250 mL beaker, again leaving all solid particles in
the 100 mL beaker. Discard the rinse water in the 250 mL beaker.
* The conversion of copper (II) hydroxide to copper (II) oxide is a decomposition reaction, where water is driven out of the copper (II) hydroxide with heat. Complete the word equation for this reaction. Write and balance the formula equation for this reaction in the analysis section. CONVERSION 4
13. Add 20 mL of 3M sulfuric acid (hydrogen sulfate) solution (CAUTION!) to the black copper (II) oxide in the
beaker. Stir gently. The oxide should dissolve within a minute or so. Note color of product.
* When sulfuric acid(hydrogen sulfate) reacts with copper (II) oxide, a salt and water form. Complete the word equation for the Conversion IV reaction. Write and balance the formula equation for this reaction in the analysis section. CONVERSION 5
14. Using a weigh boat obtain 2-3 grams of granular zinc (no need to record the mass). Slowly add the zinc to the
copper (II) sulfate solution which resulted from the last conversion and immediately cover the beaker with a
watch glass.
15. Allow the beaker to stand as the reaction proceeds. Occasionally, stir the reaction mixture with a stirring rod to
break up the clump of copper metal which forms. Make observations on the nature of the reaction.
16. For the reaction to be complete, all the blue color should disappear and all the excess zinc should dissolve. If all
the blue color has not disappeared, add a few more granules of zinc. If all the zinc has not reacted, add
approximately 10 mL more sulfuric acid.
17. Let the beaker stand until the zinc metal completely disappears. Since the reaction produces hydrogen gas, the
absence of bubbles will indicate when the zinc metal is all consumed. Again, break up any clumps of copper and
then let the beaker stand until the copper settles out.
18. Decant (pour) off the clear liquid into the same 250 mL beaker used before. Wash the copper in the beaker three
times with 20 mL portions of distilled water, stir vigorously, and let settle, decanting the wash water each time
into the 250 mL beaker. Don't lose any copper. Discard wash water.
19. Place the beaker in the oven to dry overnight.
20. Obtain your beaker from the oven and allow it to cool.
21. Determine the mass of the beaker plus copper and record. Deposit the copper in the container provided. Clean,
dry, and return the 100 mL beaker.
* There are two reactions occurring in this conversion: the single displacement reaction of zinc reacting with copper(II) sulfate solution, and the single displacement reaction of zinc reacting with sulfuric acid. Complete the word equations for both these reactions. Write and balance the formula equations for these reactions in the analysis section. Chemistry Lab
Reactions of Copper
Name__________________________________
Date _________________________Period____
PURPOSE: ___________________________________________________________________
_____________________________________________________________________________
DATA:
Substance
Conv 1
copper
Day One
nitric acid
Formula
Color
Phase
Quantitative
Day One:
mass beaker
____________g
copper(II) nitrate
mass Cu before rxn
nitrogen dioxide
Conv 2 & 3
sodium hydroxide
Day Two
copper(II) hydroxide
____________g
beaker + Cu before rxn
____________g
sodium nitrate
copper(II) oxide
Conv 4 & 5
sulfuric acid
Day Four:
beaker + Cu after rxn
Day Three
copper(II) sulfate
____________g
zinc
zinc sulfate
hydrogen gas
ANALYSIS:
Day One:
CONVERSION 1
(1)Word equation: copper + nitric acid → copper(II) nitrate + nitrogen dioxide + water Formula equation:
Day Two:
CONVERSION 2
(2)Word equation: hydrogen nitrate + sodium hydroxide →
Formula equation:
(3)Word equation: sodium hydroxide + copper (II) nitrate →
Formula equation:
mass Cu after rxn
____________g
CONVERSION 3
(4)Word equation: copper (II) hydroxide → copper (II) oxide + Formula equation:
Day Three:
CONVERSION 4
(5)Word equation: hydrogen sulfate + copper (II) oxide →_______________________________________
Formula equation:
CONVERSION 5
(6)Word equation: zinc + copper (II) sulfate →________________________________________________
Formula equation:
(7)Word equation: zinc + hydrogen sulfate →_________________________________________________
Formula equation:
3. PERCENT RECOVERY:
final Cu mass
% recovery = original Cu mass
x 100
=
= ______%
CONCLUSION:
1. Complete the following flow diagram for the chemical changes which occurred to the copper sample
during the conversions accomplished. Show both name and formula.
copper
Cu
copper
Cu
2. Based on the flow diagram above and the result of the calculation of % recovery, how does this
experiment relate to the Law of Conservation of Mass.
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
3. Classify each of the seven reactions according to the following types of chemical reactions. The
possible types of chemical reactions are: single replacement reactions, double replacement reactions
(precipitation or neutralization), decomposition reactions, synthesis reactions, and oxidation-reduction
reactions.
1.__________________________________
5._________________________________
2.__________________________________
6._________________________________
3.__________________________________
7._________________________________
4.__________________________________