THEORY
In this experiment a massed amount of copper; metal will be made to undergo a series of chemical reaction and will finally be converted into copper metal. The changes can be represented as follows:
Cu ( metal
CuSO
4
→
)
→
Cu
Cu
3
(
(
PO
NO
4
)
2
3
)
2
→
→
Cu
CuCl
2
( OH
→
)
2
Cu (
→
CuO metal )
The Law of Conservation of Matter states that matter can neither be created nor destroyed but can be transformed from one form into another. In theory then, the mass of copper obtained as a product should equal the mass of the original reactant copper. In actuality, each reaction will result in a loss of copper. The copper will adhere to glassware, stirring rods etc. Therefore, the copper in the final product will be less than the original copper mass. However, if contaminants are present, an increase in the final mass of the product may result.
This laboratory experiment will require approximately 4 hours of lab time.
Therefore, you may need to stop at the end of a specific procedure and return to it the following week. Your Instructor will instruct you as to where the appropriate place to stop the experiment may be. Additionally, as you perform this experiment, it will be necessary to preserve your copper sample from one laboratory session to the next. In order to do this, place the solution or precipitate in your lab drawer and cover the beaker with a paper towel.
GRADING
The grade for this lab will include 15 marks for the written portion and 5 marks for the copper sample that is turned in. This lab will NOT be graded unless the copper sample has been turned in. One mark will be deducted for each error or omission.

PROCEDURE
A. Preparation of copper (II) nitrate from copper wire
Mass accurately to the nearest 0.01 g approximately 1 gram of copper wire. Roll it into a small, flat coil and place the copper into a clean, dry 250 mL beaker.
Make sure that the beaker you are using is not chipped, cracked or badly scratched.
You must be very CAREFUL with the next step. It requires protective gloves and a lab coat that covers your arms.
In the FUME HOOD, you will find a corked test tube containing 10 mL of concentrated nitric acid. Place the 250 mL beaker containing the copper metal on a paper towel in the fume hood. WITH THE INSTRUCTOR WATCHING, carefully pour the nitric acid over the copper wire. Immediately pull down the fume hood cover and remove your gloves. The copper wire will be reacting with the nitric acid and forming soluble copper (II) ions. The brown fumes produced are nitrogen dioxide. Nitrogen dioxide is poisonous and is a common atmospheric pollutant from car exhaust.
When the reaction appears to have stopped, you should observe that the copper metal will no longer be evident and the solution in the beaker will be green. At this point, lift the cover on the fume-hood a SMALL amount, and with a gloved hand, gently swirl the beaker. This should result in the release of additional nitrogen dioxide gas. As the nitrogen dioxide dissipates, the copper solution will become a blue colour. The blue colour indicates the presence of copper (II) nitrate.
Add approximately 10 mL of distilled water to the copper (II) nitrate solution in the beaker.
Proceed to Procedure B.

B. Preparation of copper (II) hydroxide from copper (II) nitrate
In the fume hood, set up a cold water bath that will safely contain a 250 mL beaker. Place the copper (II) nitrate solution in the cold water bath ensuring that the beaker does not tip and water from the cold bath does not enter the beaker.
Using a medicine dropper and while continuously stirring, add 6 mol/L sodium hydroxide to the solution of copper (II) nitrate. The pale blue precipitate that forms is copper (II) hydroxide. Initially, the precipitate will form and then dissipate when the solution is stirred. Continue adding the sodium hydroxide solution until the solution is basic as indicated by red litmus paper. Red litmus paper will turn blue if in contact with a basic solution.
Proceed to Step C.
A note of caution¸the sodium hydroxide releases heat. This is one reason that good stirring and a cold water bath are both necessary. If the solution becomes too hot, a black precipitate of copper (II) oxide will form as a result of the thermal decomposition of the copper (II) hydroxide. If this happens, talk to your instructor.

C. Preparation of copper (II) oxide from copper (II) hydroxide
Add 100 mL of distilled water to the copper (II) hydroxide solution.
In the fume hood, place a hot plate and beaker tongs. Heat the solution of copper (II) hydroxide on the hot plate while continuously stirring. Bring the solution to a boil. The blue copper (II) hydroxide will be converted by thermal decomposition to a precipitate of copper (II) oxide.
Using the beaker tongs remove the copper (II) oxide solution from the hot plate and place it on the counter in the fume hood. Remove the stirring rod. Leave it for about 10 minutes to cool. Do not agitate the beaker.
After the copper (II) oxide has settled, carefully decant and discard about two thirds of the liquid in the beaker. Transfer the remaining one third of the liquid and the copper (II) oxide precipitate to a 600 mL beaker.
Proceed to step D.
D. Preparation of copper (II) sulfate from copper (II) oxide.
In a graduated cylinder, measure out approximately 25 mL of 6 mol/L sulfuric acid. In the fume hood, add the sulfuric acid to the copper (II) oxide. Gently agitate the beaker. This should yield a clear blue solution of copper (II) sulfate.
Proceed to step E.

E. Preparation of copper (II) phosphate from copper (II) sulfate
In the fume hood, with the use of a cold water bath and continuous stirring, add 6 mol/L sodium hydroxide with an eyedropper to the copper (II) sulfate solution.
Continue to add the sodium hydroxide until a blue precipitate of copper (II) hydroxide begins to persist. The copper (II) hydroxide should not dissipate when you stir the solution. The sodium hydroxide is added to neutralize the excess sulfuric acid that was introduced in procedure D and to turn the solution slightly basic.
Next, add approximately 40 mL of 1.0 mol/L sodium phosphate. Stir the solution thoroughly. The light blue precipitate that forms is copper (II) phosphate.
Test the solution with blue litmus paper until the blue litmus paper remains blue.
If the litmus paper turns red, this indicates that the solution is acidic and you must add more sodium hydroxide (remember the cold bath, eyedropper and continuous stirring).
Add approximately 60 mL of distilled water to the copper (II) phosphate. Stir well.
It is now necessary to remove all of the excess ions that have accumulated in the beaker. In order to do this, you will separate the copper (II) phosphate precipitate by filtration. The copper (II) phosphate is a fine precipitate and will require a Buchner funnel and microfiber filter paper.
Set up a Buchner funnel with a trap. Connect this to the vacuum outlet on the lab counter. Pour the contents of the beaker containing the copper (II) phosphate into the Buchner funnel. The last traces of solid copper (II) phosphate should be flushed from the beaker onto the filter with a few milliliters of distilled water from a wash bottle. Wash the precipitate on the filter at least twice with distilled water.
To do this, add enough distilled water to completely cover the precipitate and then let it stand until all of the water has run through the filter.
Proceed to step F.

F. Preparation of copper (II) chloride from copper (II) phosphate
Support the Buchner funnel containing the copper (II) phosphate with a retort stand and an iron ring. Place a clean 250 mL beaker under the Buchner funnel.
Set this up so that the bottom of the Buchner funnel is five centimeters below the top of the beaker and the funnel touches the side of the beaker. Using a 100 mL graduated cylinder measure out 50 mL of 6.0 mol/L hydrochloric acid. Carefully and slowly pour the hydrochloric acid over the copper (II) phosphate precipitate.
The precipitate will dissolve and the solution will run through the funnel into the beaker. If some of the precipitate does not dissolve, use an eyedropper to collect a few milliliters of solution from the beaker. Place this solution over the precipitate that has not dissolved. Continue until all of the precipitate has dissolved.
Proceed to Step G.

G. Preparation of copper metal from copper (II) chloride
(This step must be continuous. Do not split it up)
In the fume hood, while using an ice bath and an eyedropper, add about 25 mL of 6.0 mol/L sodium hydroxide to the copper (II) chloride solution. This should neutralize some of the excess hydrochloric acid in the solution. There should not be a precipitate present.
In a weighing boat, accurately weigh out about 2.5 g of magnesium metal to the nearest 0.01 g.
In the fume hood, place the beaker containing the copper (II) chloride in an ice water bath. Using tweezers carefully drop a small piece of magnesium metal into the copper (II) chloride solution. DO NOT STIR. As the reaction proceeds, magnesium replaces copper in the copper (II) chloride and metallic copper precipitates out. Continue to add the magnesium metal until all of the copper has precipitated out.
Accurately, to the nearest 0.01 g weigh a piece hardened #4 filter paper (not microfibre paper).
When the copper metal has completed precipitating out, filter the copper metal using the weighed filter paper in a Buchner funnel. Wash the copper metal at least five times with distilled water. If not washed properly, impurities will appear as yellowish or greenish colorations in the copper sample. After the final rising, place the filter paper and copper in an initialed beaker and place it in the oven to dry for 1-2 days.
When the sample has dried, remove the beaker from the oven; allow it to cool.
Weigh the dried filter paper and copper sample. Determine the mass of your copper sample. Return the filter paper and copper to the beaker. Using masking tape, place your name on the beaker containing the copper product and turn it in for grading.

DATA AND OBSERVATIONS
Prepare a data table which includes quantities of all reagent used in each step and associated observations.
For each procedure, include the balanced equations for each chemical reaction that occurred.
CALCULATIONS
Determine the percentage yield of copper.
Pr
Percentage yield =
100