PERCENT COMPOSITION
Background:
Copper (II) sulfate will react with iron to produce iron (II) sulfate and copper metal. Copper (II) sulfate exists
as a pentahydrate crystal, CuSO4•5H2O.
Copper (II) sulfate + iron metal  iron (II) sulfate + copper metal
Prelab: write Purpose, Procedure and prepare a data table.
Purpose: Determine percent yield of copper.
Materials: 100 mL and 250 mL beakers, Bunsen burner, copper (II) sulfate, glass rod, spatula, iron filings,
heating apparatus, filter paper, and tongs
Procedure:
1. Find the mass of a clean, dry 100 mL beaker. Record the mass in a table like the one below. Tare the
balance and add approximately 8.00 g of copper sulfate crystals to the beaker. Record the exact
mass.
2. Measure 50.0 mL of water using a beaker and add the water to the crystals in the beaker.
3. Set up the heating apparatus as demonstrated by your teacher.
4. Place the Bunsen burner below the ring. Place the beaker on the wire gauze. Carefully heat the mixture
in the beaker, but do not allow the mixture to boil. Use a blue flame for heating.
5. If the solution starts boiling turn the flame down or remove the Bunsen burner for a few minutes.
6. Continue heating and stirring the mixture with the glass rod until all the crystals are completely
dissolved. Turn off the burner.
7. Measure 1.50 g of iron filings using filter paper to place the filings on.
8.
Add the iron filings, at little at a time, to the hot copper (II) sulfate solution, stirring continuously. Heat
the beaker again. Remove the burner if the solution starts to boil.
9. When all the iron has disappeared turn off the burner and let the beaker cool. Allow the beaker to cool
for 5 to 10 min.
10. Pour most of the liquid into the 100 mL beaker. Then pour the liquid in the waste bucket.
11. Find the mass of a piece of filter paper.
12. Remove the copper from the 250-beaker using a spatula and place it on the filter paper.
13. Allow the copper to dry out overnight.
14. After the solid is completely dry, find the mass of the filter paper and the solid copper. Record this mass
in your data.
Data
1. Qualitative observations: describe any color changes that occurred.
2. Data table for copper sulfate and iron reaction. Give this table a title. Cut and paste in your notebook or
create your own table in your notebook.
Mass of copper sulfate (g)
Mass of dry filter paper (g)
Mass of dry filter paper and copper (g)
Mass of iron (g)
Calculations
Show work for the following.
1. Which was the limiting reactant? How do you know?
2. Determine the theoretical yield of copper (grams) that you should produce from the amount of limiting
reactant that you started with.
3. What is your actual yield of copper?
4. Determine the percent yield of copper.
5. What was the excess reagent? How many grams of excess reagent remained?
Give this table a title.
Theoretical yield of copper
Actual yield of copper
Percent yield of copper
Grams of ____________ remaining
Conclusions Did you get more or less than 100% yield? What does this mean about the purity of your
product (Is it pure or are there some impurities?)?
Evaluations: Answer only #1 or #2.
1. If you had less than 100% yield, give two possible reasons why. How could you improve the procedure
to get closer to 100% yield.
2. If you had more than 100% yield, identify the possible impurities. How could you improve the
procedure to reduce the amount of impurities?