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Topics: Redox, Hydrogen, Oxidizing agent Pages: 10 (5692 words) Published: October 27, 2014
INVESTIGATION

12.A

Target Skills
Determining the reactivity of various metals

Testing Relative Oxidizing and Reducing
Strengths of Metal Atoms and Ions
By observing whether reactions occur between solid
metals and metal ions in solution, you can determine
the order of oxidizing and reducing agents according to
strength.
Question
How can the presence or absence of a reaction provide
information about the relative strength of oxidizing and
reducing agents?
Safety Precautions



Wear goggles, gloves, and an apron for all parts of this
investigation.



If you spill any solution on your skin, wash it off with
large amounts of water.



Wash your hands when you have completed the
investigation.

Materials
• 4 small pieces of each of
the following metals:
- aluminium foil
- thin copper wire or tiny
copper beads
- iron filings
- magnesium
- zinc






dropper bottles
containing dilute
solutions of
- aluminium sulfate
- copper(II) sulfate
- iron(II) sulfate
- magnesium sulfate
- zinc nitrate
well plate
white paper

Procedure
1. Place the well plate on a piece of white paper.
Label the paper to match the data table below.
Metal

Compound

Al2(SO4)3(aq) CuSO4(aq) FeSO4(aq) MgSO4(aq) Zn(NO3)2(aq)

Al(s)
Cu(s)
Fe(s)
Mg(s)
Zn(s)

438 MHR • Unit 6 Electrochemical Changes

Analyzing data to derive a simple
reduction table
Using appropriate numeric and symbolic
modes of representation to communicate
equations

2. Place the four small pieces of each metal, about
the size of a grain of rice, into the well plate. Use
the data table as a guide for placement of metals.
Cover each piece of metal with a few drops of the
appropriate solution. Wait 3–5 min to observe
whether a reaction occurs.
3. Look for evidence of a chemical reaction in each
mixture. Record the results by using a “y” for a
reaction and an “n” for no reaction. If you are unsure,
repeat the process on a larger scale in a small test tube.
4. Discard the mixtures into the waste beaker
supplied by your teacher. Do not pour anything
down the drain.
Analysis
1. For each single-replacement reaction that
proceeded spontaneously, write
a) a complete balanced equation
b) an ionic equation
c) a net ionic equation
2. Identify the oxidizing agent and the reducing
agent in each of the reactions that proceeded
spontaneously.
3. Make a simple redox table similar to Table 12.1
that contains all the metal atoms and metal ions
that you analyzed in this investigation. Note that
the ion that was able to oxidize all other metal
atoms is placed at the top of the left column. In the
next row, place the ion that oxidized all but the first
metal atom. Complete the table.
Conclusion
4. Based on your observations, do you think that there
are any properties of metal atoms or ions that would
allow a chemist to predict whether one would be a
better oxidizing or reducing than another? Explain
your reasoning.

Predicting the Spontaneity of Redox Reactions
Table 12.2 Oxidation-Reduction Table
An analysis of the redox table that you created
Strongest Oxidizing Weakest Reducing
in Investigation 12.A shows you that metal
Agent
Agent
ions can act as oxidizing agents because they
Au+(aq)
Au(s)
can remove electrons from certain metal
Pt2+(aq)
Pt(s)
Ag2+(aq)
Ag(s)
atoms. Likewise, metal atoms act as reducing
Hg2+(aq)
Hg(s)
agents because they can donate electrons to
Cu2+(aq)
Cu(s)
certain ions. By performing many experiments
Sn2+(aq)
Sn(s)
Ni2+(aq)
Ni(s)
similar to those in Investigation 12.A, chemists
2+(aq)
Co
Co(s)
have determined the relative strengths of many
Tl+(aq)
Tl(s)
ions as oxidizing agents and atoms as reducing
Cd2+(aq)
Cd(s)
agents. Table 12.2 lists the results of some of
Fe2+(aq)
Fe(s)
Cr3+(aq)
Cr(s)
those experiments. Notice that the strength of
Zn2+(aq)
Zn(s)
the ions as oxidizing agents increases as you go
Al3+(aq)
Al(s)
up the...
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