_Chemical Equilibria _
By: Bob Marely
Darryl Fagan Pd. 4 01-20-00 AP Chemistry An Activity Series Chemistry Lab 5
Introduction; In this experiment you will study some metals and some
nonmetals to find their relative reactivity. A ranking according to reactivity
is called an activity series. For example, an activity series containing the
elements calcium, gold and iron would put the reactive calcium at the top,
iron in the middle, and the unreactive gold at the bottom. If a piece of iron
metal is placed in a solution of gold nitrate, the iron will dissolve forming
positive ions while the solid gold metal appears. The more reactive metal will
displace ions of the less reactive metal from solution. The less reactive
element will appear as the solid elementPurpose; To determine an activity
series for metals using a microscale technique, and to determine an activity
series for halogens using a solvent extraction technique Procedure; a.
Determine an activity series for some metals. Place a 24-well plate so that
there are 6 wells across and 4 wells down Place 1 dropper full of copper
(II) nitrate solution in rows 2 through 4 in the first column. Put one dropper
full of magnesium nitrate in wells 1, 3, and 4 of the second column. Place 1
dropper full of lead (II) nitrate in wells 1, 2, and4 of the third column. Put
one dropper full of zinc nitrate in wells 1, 2, and 3 of the fourth column,
and put 1 dropper full of silver nitrate on each of the 4 wells in the fifth
column Put a small piece of copper metal in each of the wells containing a
solution in the first row. Add magnesium metal to each of the solutions in the
second row, lead to the third, and zinc to the fourth row. Allow to stand at
least 5 minutes. Determine if a reaction has occurred in each well by
observing if a metal precipitate has formed or if the surface of the metal has
become coated. If a metal ion is reduced by a metal, than the reserve reaction
should not occur. One metal is more reactive than another if the metal will
replace the metal ion in its compounds. Record your data Dispose of all
materials by the suggested manor of Methods #26a and #26b. b. Determine the
activity series for some halogens. In this part you will test to see if the
halogens Cl , Br ,and I ,can be reduced by the halide ion Cl , Br , and I . To
determine what products will be formed, you will need to have a test, which
will tell which halogen is present, Halogens dissolve in the nonpolar solvent
mineral oil forming different color solutions. Mineral oil does not dissolve
in water, but when shaken with an aqueous halogen solution, the halogen is
extracted from the water into the mineral oil. The color of the mineral oil
layer indicates which halogen is present First, test to see what color each
halogen shows in mineral oil. Place 1 dropper full of chlorine water, 1
dropper of Bromine water, and 1 dropper of iodine water into separate 10mm
test tubes. Add one dropper of mineral oil to each, cork the tube and shake it
for ten seconds. Let the mineral oil layer separate and record the color that
each halogen shows when dissolved in mineral oil Test to see if the halide
ions give a color to mineral oil. Place 1 dropper of NaCl, KI, and NaBr
solutions into different test tubes, add a dropper of mineral oil to each,
cork and shake to determine if the halide ions impart a color to the mineral
oil layer. Report your data React each halogen with the other two halide
ions to see if a halide ion can reduce other halogens. Place 1 dropper of NaBr
solution into one test tube and 1 dropper of KI solution into a second test
tube. Add 1 dropper of chlorine water to each, cork and shake to mix. Now add
1 dropper of mineral oil, cork and shake again. When the mineral oil layer has
separated, record its color and determine if a reaction has occurred. Record
your data. If chlorine appears no reaction has occurred, if either bromine or
iodine appears there was a reaction Repeat the test using bromine water
mixed with NaCl and KI solutions, and iodine water mixed with CaCl and NaBr
solutions Materials; 24-well plate Forceps Test tubes, 13 X 100mm Test tube
rack Cork stoppers for test tubes Copper Copper (II) nitrate, 0.1 M Zinc Zinc
nitrate, 0.1 M Magnesium Magnesium nitrate, 0.1 M Lead Lead (II), 0.1 M Silver
nitrate, 0.1 M Chlorine water Sodium chloride, 0.1 M Bromine water Sodium
bromide, 0.1 M Iodine water Potassium iodide, 0.1 M Mineral oil Method; In
the three parts of the lab, you will be using two methods, for the first
section you will be using a microscale technique. For the remaining two
experiments you will be using a solvent extraction technique Data tables;
Cu (aq) Mg (aq) Pb (aq) Zn (aq) Ag (aq) Cu (s) X No No No Yes Mg (s) Yes
X Yes Yes Yes Pb (s) Yes Yes X Yes Yes Zn (s) Yes No Yes X Yes Cl (aq) Br
(aq) I (aq) Cl (aq) X Clear-Yellow Clear Br (aq) Clear-Yellow X Clear-Yellow
I (aq) Clear Pink-Clear X Mineral Oil Yellow-Clear Clear Pink-Purple
NaCl KI NaBr Br (aq) Clear Clear X I (aq) Clear X Clear Conclusion; I
believe that this experiment though very rough in nature has completed the
purpose of administering the methods of determining activity series in metals
through a microscale technique, and determining an activity series for
halogens using a solvent extraction technique. All reactions occurred as
predetermined by their placement on a textbook reactivity series, and no
errors occurred in the collection of data. The experiment contained no
possibility of error, the reactions either work or do not work. Discussion;
1.) Write balanced net ionic equations for all reactions that occurred with
metals. Cu (s) + 2Ag (aq) Þ Cu (aq) + 2Ag (s) Mg (s) + Cu (aq) Þ Mg (aq) + Cu
(s) Mg (s) + Pb (aq) Þ Mg (aq) + Pb (s) Mg (s) + Zn (aq) Þ Mg (aq) + Zn (s) Mg
(s) + 2Ag (aq) Þ Mg (aq) + 2Ag (s) Pb (s) + Cu (aq) Þ Pb (aq) + Cu (s) Pb (s)
+ Mg (aq) Þ Pb (aq) + Mg (s) Pb (s) + Zn (aq) Þ Pb (aq) + Zn (s) Pb (s) + 2Ag
(aq) Þ Pb (aq) + 2Ag (s) Zn (s) + Cu (aq) Þ Zn (aq) + Cu (s) Zn (s) + Pb (aq)
Þ Zn (aq) + Pb (s) Zn (s) + 2Ag (aq) Þ Zn (aq) + 2Ag (s) 2.) List the metals
in order of decreasing ease of oxidation. Compare your list with the activity
series found in the textbook. How do the two lists correlate? Test
Results Text Book Magnesium Magnesium Lead Lead Zinc Zinc
Copper Copper Silver Silver · The two results correlate precisely as
they should. 3.) Write half-reactions for each of the meal ions. Arrange the
reaction list in order of decreasing ease of reduction. Compare your listing
with a listing found in a table of standard reduction potentials. How do the
two lists correlate? Cu + 2Ag Þ Cu + 2Ag Cu Þ Cu + 2e- 2Ag + 2e- Þ 2Ag Mg +
Cu Þ Mg + Cu Mg Þ Mg + 2e- Cu + 2e- Þ Cu Mg + Pb Þ Mg + Pb Mg Þ Mg +2e- Pb
+ 2e- Þ Pb Mg + Zn Þ Mg + Zn Mg Þ Mg + 2e- Zn + 2e- Þ Zn Mg + 2Ag Þ Mg + 2Ag
Mg Þ Mg + 2e- 2Ag + 2e- Þ 2Ag Pb + Cu Þ Pb + Cu Pb Þ Pb + 2e- Cu +2e- Þ Cu
Pb + Mg Þ Pb + Mg Pb Þ Pb + 2e- Mg + 2e- Þ Mg Pb + Zn Þ Pb + Zn Pb Þ Pb +
2e- Zn + 2e- Þ Zn Pb + 2Ag Þ Pb + 2Ag Pb Þ Pb + 2e- 2Ag + 2e- Þ 2Ag Zn +
Cu Þ Zn + Cu Zn Þ Zn + 2e- Cu + 2e- Þ Cu Zn + Pb Þ Zn + Pb Zn Þ Zn +
2e- Pb + 2e- Þ Pb Zn + 2Ag Þ Zn + 2Ag Zn Þ Zn + 2e- 2Ag + 2e- Þ 2Ag A;
order of occurrence according to data B ; order of occurrence according to
textbook 4.) Explain what is meant by solvent extraction. Solvent extraction
is the process in which two substances integrated with different substances
that can not combine are introduced and the ensuing reaction occurs with no
interference from the two solvents. In this case water and mineral oil were
the two substances, these substances readily separate when introduced and
therefore are ideal candidates for this technique. 5.) How can you tell if a
reaction occurs in the halogen experiment? When a reaction occurs in the
halogen experiment there are loose ions floating in the solution. Different
substances give off different color ions, and the base solvent do not have an
interchange of ions, therefore if there is no color to the solution, no
reaction may have occurred because of the lack of change in color. If the
fluid mixture however does change in color, there was an exchange of
electrons, and the now colorful ions are present in the solution. 6.) Why
should you not expect the halide ion to dissolve in mineral oil? Mineral oil
is a highly neutral substance and reacts with nothing, it will also not mix
with other fluids making it ideal for the solvent extraction technique used in
determining the activity series for the halogens.
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