Stoichiometry The Reaction of Iron With Copper II Sulfate

Activity 2
Stoichiometry: The Reaction of Iron with Copper

II Sulfate
Stoichiometry is the study of the relationships of the amounts of two or more substances
undergoing a chemical reaction.
In this experiment we will use stoichiometric principles to deduce the appropriate
equation for the reaction between metallic iron and a solution of copper (II) sulfate. This reaction
produces metallic copper, which is seen precipitating as a finely divided red powder. This type of
reaction, in which one metal "displaces" another from a solution of one of its salts, is known as a
single substitution reaction. A metal capable of displacing another from a solution of one of its
salts is said to be "more active" than the displaced metal. In this experiment, iron is more active
than copper.
Iron forms 2 types of ions, namely Fe2+ and Fe3+. We shall use stoichiometric principles
to determine which of these ions is formed in the reaction between iron and copper (II) sulfate
solution. If Fe2+ is formed, then equation (5.1) is correct, while equation (5.2) is correct if Fe 3+ is
formed. Your task is to find out which equation is consistent with the results of your experiment.
Equation 5.1: Fe(s) + CuSO4(aq)  FeSO4(aq) + Cu(s)

Fe(s) + Cu+2(aq)  Fe+2(aq) + Cu(s)
Equation 5.2: 2Fe(s) + 3CuSO4(aq)  Fe2(SO4)3(aq) + 3Cu(s)

2Fe(s) + 3Cu+2(aq)  2Fe+3(aq) + 3Cu(s)
An excess of copper (II) sulfate solution (to make sure that all the iron is reacted) will be
added to a known amount of iron. The metallic copper produced will be weighed. These
weighings will be used to calculate the moles of iron used and the moles of copper formed. If
equation (5.1) is correct, the moles of copper should equal the moles of iron. If equation (5.2) is
correct, we should obtain 1.5 moles of copper per mole of iron.
INTENDED LEARNING OUTCOMES (ILO)

At the end of this activity, the students should be able to:
1. Calculate the number of moles of the metal that is reduced in a redox reaction;
2. Predict the form of Fe ion that undergoes oxidation against Cu in CuSO4(aq); and
3. Demonstrate a basic analytical skill in determining the amount of product in a chemical
reaction.
APPARATUS
Beaker, 100 mL or 250 mL (3) Erlenmeyer flask
Bunsen burner/Hot plate Spatula
Graduated cylinder Wash bottle
Glass rod/stirrer
CHEMICALS
Liquids: Copper (II) sulfate solution Solid: Iron powder
Distilled water
Acetone
PROCEDURE
1. Conduct this experiment in triplicate manner.
2. Weigh a clean, dry 100 mL or 250 mL beaker.
3. Accurately weigh 1.00 gram of iron powder into the beaker. Do not exceed 1.00 gram.
4. Measure 30 mL of 1.0 M CuSO4 solution into a graduated cylinder. Pour it into an
Erlenmeyer flask, heat gently to almost boiling.
5. Slowly add the hot CuSO4 solution into a graduated cylinder. Be sure the addition is slow
to avoid excess frothing and possible loss of material. It will help to avoid frothing if a
wooden applicator stick is placed in the beaker before adding the hot CuSO4 solution.
6. Swirl the flask to insure completeness of reaction. When the reaction has ceased, allow
the copper product to settle. Then carefully decant the liquid from the copper, (pour off
the liquid and leave the solid behind). You may observe a thin copper colored sheen on
the surface of the liquid which does not settle out. You may ignore this.
7. Add about 10 mL of distilled water to the solid copper and swirl to wash any remaining
ions from the copper.
8. Decant the wash water from the copper and add 10 more mL of distilled water, swirl and
decant again.
9. Now add several mL of acetone (CAUTION: Acetone is very flammable) to the copper.
Swirl and allow to stand a few minutes and decant off the acetone. Repeat with a second
portion of acetone. Discard the acetone in the organic wastes bottle. The acetone readily
dissolves the water and removes it. The acetone is easily removed by gently heating or by
using a stream of air since acetone has a low boiling point and readily evaporates. We
will use gentle heat.
10. When the copper is dry, carefully dry the outside of the beaker and reweigh to find the
mass of copper formed.
11. For each run, calculate the moles of iron used and the moles of copper formed. Deduce
whether iron goes into solution as Fe+2 or Fe+3
Activity 2
Name : ________________________________________ Date:___________________
Section and Group No.: ____________________________ Score:__________________
Percentage: _____________
Stoichiometry: The Reaction of Iron with Copper II Sulfate
Write the chemical formula of the following: (1 pt. each)

Iron _____________________
Copper II Sulfate _____________________
Iron II Sulfate _____________________
Acetone _____________________
DATA AND OBSERVATIONS (2 pts. each)
Table 5.1. Reaction of Iron with Copper II Sulfate

Trial 1 Trial 2 Trial 3
a.) Mass of beaker
b.) Mass of beaker plus iron
c.) Mass of iron used
d.) Moles of iron used (MM = 55.845 g/mol)
e.) Mass of beaker plus copper
f.) Mass of copper formed

g.) Moles of copper formed (MM = 63.546
g/mol)
h.) Ratio of moles of copper to moles of iron;
Cu:Fe
(g ÷ d)
POST LAB QUESTIONS (5 pts. each)
1. From your data, which equation, correctly represents the chemical reaction that
occurred? Explain briefly.
2. What evidence indicates that a chemical reaction has occurred?
3. State two reasons why you may not obtain the theoretical amount of copper in this
experiment.
4. What do you think are the common factors that affect your result or that have cause
an error(s) to your data?
5. How can we possible reduce the errors that affects your data?

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Activity 2

Stoichiometry: The Reaction of Iron with Copper

Equation 5.1: Fe(s) + CuSO4(aq)  FeSO4(aq) + Cu(s)

Equation 5.2: 2Fe(s) + 3CuSO4(aq)  Fe2(SO4)3(aq) + 3Cu(s)

INTENDED LEARNING OUTCOMES (ILO)

Stoichiometry: The Reaction of Iron with Copper II Sulfate

Write the chemical formula of the following: (1 pt. each)

DATA AND OBSERVATIONS (2 pts. each)

Table 5.1. Reaction of Iron with Copper II Sulfate

a.) Mass of beaker

b.) Mass of beaker plus iron

c.) Mass of iron used

d.) Moles of iron used (MM = 55.845 g/mol)

e.) Mass of beaker plus copper

f.) Mass of copper formed

POST LAB QUESTIONS (5 pts. each)

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