Reactions of Metals with Aqueous Solutions of Ionic Compounds
Introduction:
The elements in the periodic table can be divided into two main groups: metals on
the left side and nonmetals on the right. Metals are the most numerous elements on the
Periodic Table. They have many properties with which most people are familiar, such as
high luster (shinning), ability to conduct heat and electricity well. Properties of metals
are dictated by the microstructure of mobile valence electrons attracting positively
charged metallic cations. Metals have some similar chemical properties. Metals tend to
have low ionization energy, hence relatively easy to lose valence electron(s) to form
cations in order to achieve electron configurations of noble gases. The tendency of metal
atom loses valence electron(s) determines chemical properties of metals. The usefulness
of metals in structural and other applications depends on their physical and chemical
properties. Although iron is the most common metal used in manufacturing and
construction, it must be protected against corrosion because iron rusts easily. Copper is
used in electrical wiring because it conducts electricity extremely well and resists
corrosion better than many metals. Gold is a highly valuable jewelry metal because it is
essentially unreactive. Chemically, metals have similarities in terms of losing valence
electrons, but the extent of how easy to lose those valence electrons differs due to variety
of reasons. How can we determine the relative reactivity of different metals?
Metals tend to be oxidized rather easily (which also means they are good reducing
agents). There are four general ways by which a metal can transfer electrons: (a) reaction
with water, (b) reaction with oxygen, (c) reaction with acids, and (d) reaction with other
metallic cations. An example of the latter is the reaction of aluminum metal with copper
nitrate to produce aluminum nitrate and metallic copper.
2 Al(s) + 3 Cu(NO3)2(aq)
2 Al(NO3)3 (aq) + 3 Cu(s)
The activity series is a listing of the metals according to their reactivity as
reducing agents. The concept is that the more active a metal is in its elemental
(uncombined) state, the more likely it is to donate electrons to a positive ion (cation) in
solution and thus replace it in the solution. In the reaction above, aluminum is more
active than copper and thus replaces copper ions in solution. Reactions of this type are
sometimes also called single replacement reactions.
Hydrogen is usually included in the activity series. (In this case hydrogen is
considered a metal!) Metals more active than hydrogen are considered the "active"
metals, those less active than hydrogen are considered "inactive."
Purpose:
The student will investigate reactivity of metals in aqueous solutions of various
ionic compounds and hydrochloric acid.
Materials / Equipment:
Copper
Zinc
Magnesium
Aluminum
0.20 M silver nitrate aqueous solution
3.00 M HCl (hydrochloric acid)
0.20 M magnesium nitrate aqueous solution
microplate
0.20 M copper(II) nitrtate aqueous solution
spatula
0.20 M zinc nitrtate aqueous solution
Safety:
 Always wear safety glasses and apron in the chemistry lab.
 Never eat or drink in the chemistry lab.
 Avoid contact of all chemicals with eyes and all body tissues.
 Silver nitrate solution is toxic by ingestion and irritating to body tissue. It also
stains skin and clothing. Zinc nitrate solution is slightly toxic by ingestion and
corrosive to body tissue. Copper(II) nitrtate solution is slightly toxic by ingestion;
it is irritating to skin, eyes, and mucous membranes. Magnesium nitrate solution
is a body tissue irritant. 3M hydrochloric acid is corrosive and irritating to skin.
 Always dispose waste chemicals according to approved practices.
Pre-lab Questions:
1. How can you tell if a chemical change takes place? What are the major signs of
chemical reactions?
2. Write the correct formula units for all the ionic compounds.
3. When salts of ionic compounds dissolve in water, what actually happened on the
ionic level?
4. What is the meaning of the unit M?
5. Why water is a great solvent for many salts?
6. Draw models on the ionic/atomic/molecular level for metal, ionic compounds,
water, and ionic compounds dissolved in water.
7. What are the hypotheses for this lab?
8. Set up date table in lab notebook.
Procedure:
1. Use the microplate shown above. Each well should be used for one reaction. The
microplate is labeled as shown in the right half of the above image. The grid
system can be used to keep track of reactions. Each row should be assigned to one
metal. Each column should be assigned to either an aqueous solution of an ionic
compound or hydrochloric acid.
2. Use distilled water to wash each cell carefully.
3. Use the spatula to carefully transfer small amount of each metal into 5 wells on
the same row. Metals are copper, zinc, aluminum and magnesium. For example,
5 wells in row A is covered with copper, row B with zinc, row C with aluminum,
and row D with magnesium. Note: do not put too much metal into the wells.
4. Each metal will be reacting with each aqueous solution of various ionic
compounds and hydrochloric acid. Fill wells in the first column (A1, B1, C1, and
D1) with one aqueous solution, the 2nd column with another aqueous solution, and
so on until 4 aqueous solutions are occupying 4 columns of wells. For example, if
the first ionic compound to be test is chosen to be magnesium nitrate, the solution
will be added on top of the metals in all 4 wells in the first column. The last
column of wells should be mixed with hydrochloric acid.
5. Observe carefully and record in details.
6. Wait for 5 minutes. Observe again and carefully record in details.
7. Dispose the contents according to instruction by the teacher.
8. Wash the microplate thoroughly first with tap water, then rinse 3 times with
distilled water.
Data Analysis:
 Organize data analyses in tabulated form.
 Find trends in the data in terms of reactivity. Rank metals from least reactive to
most reactive.
Post-lab Questions:
Read Pearson online textbook, Chapter 11 “Chemical Reactions”. Pay close attention to
the section about single-replacement reactions. In addition, use the following links to gain
further understanding of reactivity series (metals and halogens) and single-replacement
reactions.
http://en.wikipedia.org/wiki/Metal_reactivity
http://en.wikipedia.org/wiki/Single_displacement_reaction
1. Why is the instruction given at the beginning of the lab to wash the microplate
with distilled water?
2. Did all mixtures produce signs of chemical reactions? Summarize your
observations in a tabulated, easy to understand format in data analysis section.
3. What is the key difference among those aqueous solutions?
4. Which metal reacts with most of the aqueous solutions? Which metal reacts with
least?
5. Which metal reacts most vigorously with HCl? Which metal reacts the least?
6. Can the reactivity of metals (copper, zinc and magnesium) be ranked? Explain
your answer.
Extension Questions:
1. Write the balanced chemical equations with all reactions observed in the lab.
2. Can the reactivity of sodium, lithium, potassium, and magnesium metals ranked
using the approach utilized in this lab? Explain your answer.