A SERIES OF REACTIONS INVOLVING COPPER COMPOUNDS
Day 1:
Use word reactions in bold below and write formulas and balance reactions on your answer
sheet.
PRECAUTIONS:
ANY BLUE SUBSTANCE/LIQUID may not be poured down the drain and must be
disposed of properly
Several ACIDS and one strong BASE are used in this lab. Any burning/tingling/itching
should be rinsed off at the sink immediately.
Day 2
REACTION ONE:
Copper reacts with nitric acid and forms copper (II) nitrate, nitrogen dioxide, and water
Obtain a sample of Copper (100-200mg) and place the copper in the test tube. Add 40 drops
of 8M HNO3 (nitric acid). This should be done in the hood. Briefly observe the reaction that is
taking place. The brown gas produced by this reaction is nitrogen dioxide (smog). Smog is not
good for you, so breathe as little as possible. The blue color of the solution is characteristic of
many copper compounds which are dissolved in water.
Reaction is complete when there is no longer any solid copper in the test tube and the solution
is deep blue/green. This reaction will be left overnight to finish.
DAY 3:
REACTION TWO:
Copper (II) nitrate reacts with sodium hydroxide to produce copper (II) hydroxide and
sodium nitrate
Troubleshooting:
Inspect test tube. If at any time today you notice that there is any solid copper left then
request another test tube ask permission to carefully transfer the blue/green liquid to another test
tube.
SIDE REACTION: nitric acid also reacts with sodium hydroxide to form water and
sodium nitrate.
Point the test tube away from anyone and add to the solution slowly 3M NaOH (sodium
hydroxide). Stir gently. The solid that forms is called copper (II) hydroxide. After nothing else
seems to be happening as you add the 3M NaOH then you will need to begin testing your
solution with litmus paper to see if it is Basic or not. Make sure that test tube is well mixed
before testing. To do this transfer a drop of WELL MIXED solution on the stirring rod onto the
piece of litmus paper. Do not place the litmus paper itself into the solution. Try not to get any of
the blue solid onto the stirring rod.
Clean up: litmus paper can go in the trash can & rinse off stirring rod.
Reaction is complete when the litmus paper turns blue to indicate a basic solution.
REACTION THREE
Copper (II) Hydroxide upon heating produces Copper (II) oxide and water
Place the test tube in a warm water bath (hot plate setting 5). Stir reaction to make sure
substances are well mixed while warming. This may sit overnight.
DAY 4
Reaction is done when no blue color remains. *(See note about remaining blue color below).
Troubleshooting:
*blue color remaining at the bottom of the test tube with some brown on top may indicate that
the reaction needs better mixing. Stir reaction. Recheck with litmus paper to make sure that
reaction is basic. Add a few drops of NaOH as necessary.
*blue color and blue solid with little or no black substance may indicate that the entire mixture
was not in fact basic. Recheck with litmus paper and add more NaOH until the litmus paper turns
blue.
Reaction work up when finished: The dark brown-black precipitate is copper (II) oxide. The
copper oxide needs to be washed off. To do this let the solid settle to the bottom of the tube and
remove as much of the liquid at the top of the test tube with a pipet. Be careful not to get any
brown solid into the pipet. Add a few ml of distilled water and let the solid settle to the bottom
again. Remove the liquid at the top again. Repeat this rinse step one more time. Do not remove
any of the copper oxide.
DAY 5
REACTION FOUR
Copper (II) oxide reacts with sulfuric acid to produce copper (II) sulfate and water.
Add dropwise 6M H2SO4 (sulfuric acid) to the copper (II) oxide. Stir as needed. The copper (II)
oxide will dissolve.
Reaction is complete when there is no remaining black solid and a clear blue solution of
copper (II) sulfate remains.
REACTION FIVE
Copper (II) sulfate reacts with zinc metal to form zinc (II) sulfate) and copper
SIDE REACTION: Zinc metal reacts with sulfuric acid to form hydrogen gas and zinc
sulfate
Add a few granules of zinc to the test tube. You will see hydrogen gas bubbles being generated
as the zinc also reacts with the acid. You will notice the brownish red copper metal forming in
the test tube. This reaction produces some heat so you may also notice the test tube warming.
Add more zinc when reaction the zinc is used up or the reaction seems too slow. Do not add too
many as this may leave zinc remaining or overheat the reaction. Stir to keep bubbles from
bubbling over.
Caution: Test tube may get hot.
Reaction is complete when no blue color remains in solution. If blue remains gently heat, add
more zinc.
Day 6
If the reaction is not complete add more granules of zinc. When no blue color remains in
solution then filter copper. Grade will be based on the quantity and quality of copper.