Moles of Iron and Copper
The mole is a convenient unit for analyzing chemical reactions. The mole is equal to 6.02 x 10 23
particles, or Avogadro’s number of particles. More important, however, than the number of particles
in a mole is the mass of a mole of any compound or element. It is the mass in grams corresponding
to the molecular, formula, or atomic mass. Simply stated, the mass of one atom of copper is 63.5
amu; the mass of one mole of copper atoms is 63.5 grams. Similarly, the mass of one molecule of
water is 18.0 amu; the mass of one mole of water molecules is 18.0 grams.
In this experiment, you will observe the single replacement reaction of iron with copper(II) chloride
solution. You will determine whether the iron chloride produced is iron(II) chloride or iron(III) chloride.
Objectives:
1. You will determine the number of moles of copper produced and the number of moles of iron used
in the reaction of iron and copper(II) chloride.
2. You will calculate the ratio of moles of iron to moles of copper.
3. You will infer the formula and the name of the iron chloride produced.
Materials:
Apparatus
safety goggles
2 100 mL beakers
wash bottle
stirring rod
drying oven
plastic forceps
paper towels
centigram balance (to 0.01g)
Reagents
copper(II) chloride
2 iron nails
1M hydrochloric acid, HCl
distilled water
Safety:
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Wear your safety goggles at all times during the experiment.
Do not pour solutions down the sink.
Wash hands immediately if you come into contact with reacting liquids.
Wash hands thoroughly at the end of the experiment.
Pre-Lab Questions: (Hint: read the procedure first!)
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7.
How many moles are present in a sample of 34 g of iron? (show work!)
What is the mass of 1 mole of copper? (show work!)
Why do we need to wash the copper in this experiment?
Define the word decant.
How will you determine the mass of iron lost from the nail during the reaction?
Write the formula of iron(II) chloride and of iron(III) chloride.
Write the balanced chemical equations for the single replacement reactions that describes the
formation of each formula of iron chloride (iron(II) chloride and of iron(III) chloride).
Procedure:
1. Put on your safety goggles.
2. Use a small piece of colored tape from the teacher’s desk to label a 100 mL beaker with your
period and bench number. This will be your reaction beaker (the beaker used for the reaction).
3. Weigh and record the mass of the 100 mL reaction beaker.
4. Weigh about 2 g of copper(II) chloride and add it to the reaction beaker.
5. Add approximately 15 mL of distilled water to the copper(II) chloride and to make a solution.
6. Use a stirring rod to make sure all of the copper(II) chloride crystals have dissolved.
7. Obtain two clean, dry nails. Check to make sure that the nails can rest on the bottom of the
beaker. If necessary, bend the nails with pliers to fit the beaker.
8. Weigh and record the mass of the nails to the nearest 0.01 gram.
9. Place the nails in the copper(II) chloride solution. Leave the nails undisturbed for approximately
20 minutes. During that time, you should see the formation of copper in the beaker. At the same
time, some of the iron will react.
10. Use the plastic forceps to carefully pick up the nails, one at a time. Use the wash bottle to rinse on
top of beaker any remaining copper from the nails before removing them completely. If necessary,
use a stirring rod to scrape any copper from the nails. Set the nails aside to dry on a paper towel.
11. Once dry, measure and record the mass of the nails to the nearest 0.01 gram.
12. Decant means to pour off the liquid from a container that holds both solid and
liquid. Carefully decant the liquid from the solid. Pour the liquid into another
beaker so that in case some of the solid is poured out, you can retrieve it.
13. After decanting, rinse the solid again with about 15 mL of distilled water.
Decant again. Repeat this step 3 or 4 more times.
14. Wash the solid with about 10 mL of 1M hydrochloric acid. Decant again.
Finally, wash the solid one more time with 15 mL of distilled water and decant.
15. After the final wash and decant, place the beaker with the copper in a drying oven. Be sure your
beaker has some identification so that you can retrieve it the following day.
16. Before leaving the laboratory, clean up all materials and wash your hands thoroughly.
17. The next class day, weigh and record the mass of the 100 mL beaker with the dried reaction product.
Data Table
Before Reaction
After Reaction
 Mass (g)
 moles
Mass of Beaker (g)
Mass of Nails (g)
Data Analysis: (Show all work!)
1.
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4.
Calculate the moles of iron used up in reaction.
Calculate the moles of copper produced in the reaction.
Calculate the ratio of moles of iron to moles of copper that reacted in the reaction.
Write the balanced reaction with the formula of iron chloride that you actually obtained.
Post-Lab Questions:
1. Could the same results be obtained by reacting small pieces of copper with an iron chloride
solution? Explain your reasoning. (hint: reactivity series)
2. Why does the reaction of iron and copper chloride occur?
3. Why do shipbuilders put pieces of zinc on the hulls of iron ships? (remember the composition of
salt water!)