Name: _________________________________
Oxidation States of Manganese Lab
Pre-Lab Discussion
Oxidation numbers or oxidation states are assigned to atoms in molecules to show the general
distribution of electrons among the bonded atoms. In assigning oxidation numbers, “ownership” of the
bonding electrons is given to the more electronegative atom in each bond. Unlike ionic charges, oxidation
numbers do not have an exact physical meaning. In its compounds, manganese exhibits oxidation states of a
+2 up to a +7. The more common oxidation states are +2, +4 and +7. Since the colors of the six oxidation
states are all different, you will discover which color represents each individual oxidation state by
determining the oxidizing and reducing species in each reaction.
Manganese donates (loses) electrons to more electronegative elements. The attractive force for
electrons is referred to as the electronegativity of an element. The greater the electronegativity is, the
stronger the affinity (attraction) for electrons. Those elements on the right side of the Periodic Table are
more electronegative than those on the left side because their electron shells are more nearly complete and
they tend to gain electrons to fill their shells to capacity. Those on the left side have relatively incomplete
electron shells and are thus inclined to donate (lose) electrons. Also, elements lower in the same column
(group) of the Periodic Table are larger and therefore, less electronegative. This is because of the reduced
force of attraction between the nucleus and the outer electron energy level, and because of the shielding
effect of core (inner shell) electrons.
Purpose
 To determine key components of each reaction you observe
 Note the color of each of the oxidation states of manganese.
 Match the color to the correct oxidation state.
Materials
2 x 12 well micro plates
distilled water
0.12M MnSO4, manganese sulfate
0.05M KMnO4, potassium permanganate
0.1M NaHSO3, sodium bisulfite
6M NaOH, sodium hydroxide
6M H2SO4, sulfuric acid
Prelab Questions
1.) In your own words, what do oxidation numbers show us?
2.) How are ionic charges unlike oxidation numbers?
3.) In general, why do atoms gain/lose electrons?
4.) If an elements’ oxidation number goes up, it is being oxidized or reduced. (circle one)
5.) This means that it is losing or gaining electrons. (circle one)
6.) If an elements’ oxidation number goes down, it is being oxidized or reduced. (circle one)
7.) This means that it is losing or gaining electrons. (circle one)
Procedures
Put on your goggles and apron. This lab uses a strong acid and a strong base, as well as
chemicals that can stain your clothing. Wash your hands carefully when you are finished. DO NOT
LET THE TIP OF THE DROPPER BOTTLE TOUCH THE SOLUTIONS IN THE WELLS! This will
contaminate the lab and give you incorrect results. To avoid confusion, return each solution to the tray
immediately after using it.
1. Label a white sheet of paper on the right side of six wells on the well plate as “1”, “2”, “3”,
“4”, “5” and “6”.
2. In the “1” well, place 8 drops of KMnO4. Note the color in your data table.
3. In the “2” well, place, in order, 8 drops of 6M NaOH and 4 drops of KMnO4. Add 2 drops of
NaHSO3. Wait one minute for the reaction to happen and record the final color in your data
table.
4. In the “3” well, place, in order, 8 drops of 6M NaOH and 4 drops of NaHSO3. Then add 4
drops of KMnO4. Wait one minute for the reaction to happen and record the final color in your
data table.
5. In the “4” well, place, in order, 8 drops of MnSO4 and then add 1 drop of KMnO4. Swirl the
solution carefully until you see a precipitate. Record that final color in your data table.
6. In the “5” well, place, in order, 8 drops of MnSO4 and 4 drops of 6M H2SO4. Then add 4 drops
of KMnO4. Swirl the solution carefully until the color changes. Record the final color in your
data table.
7. In the “6” well, place 8 drops of MnSO4. Note the color in your data table.
Data
Well Plate
1
2
3
4
5
6
Starting
Compound
KMnO4
Oxidation State
of Mn
in reactant
Oxidation State
of Mn
in product
XXXX
+7
XXXX
+2
Color of Mn
in product
KMnO4
KMnO4
KMnO4
MnSO4
MnSO4
Questions
1. How do you know the manganese gained or lost electrons in this lab?
2. Each of the reactions below correspond to the reactions that took place in the well plate
experiments you performed. These equations look a little weird because they are net ionic
equations, meaning they have left out any spectator ions not participating in the reaction.
Assign oxidation numbers to each element below, then identify which element is oxidized,
reduced, the oxidizing agent and the reducing agent. Once you have done this, you can go back
to your data table and fill in your “Oxidation State of Mn” as reactants and products.
Well Plate 2:___MnO41- + ___OH1- + ___SO32-  ___MnO42- + ___SO42- + ___H2O
Oxidizing Agent: ________
Element oxidized: ________
Reducing Agent: ________
Element reduced: ________
Well Plate 3: ___MnO4- + ___OH- + ___SO3-  ___MnO43- + ___SO42- + ___H2O
Element oxidized: ________
Oxidizing Agent: ________
Element reduced: ________
Reducing Agent: ________
Well Plate 4: ___MnO4- + ___HSO3-  ___SO42- + ___H2O + ___MnO2 + ___H+
Element oxidized: ________
Oxidizing Agent: ________
Element reduced: ________
Reducing Agent: ________
Well Plate 5: ___H2SO4 + ___MnO  ___SO3- + ___H+ + ___Mn2O3
Element oxidized: ________
Oxidizing Agent: ________
Element reduced: ________
Reducing Agent: ________
Well Plate 6: __MnO4- + __HSO3- + __H+  __SO42- + __H2O + __Mn2+
Element oxidized: ________
Oxidizing Agent: ________
Element reduced: ________
Reducing Agent: ________
3. Is Manganese being oxidized or reduced as it goes from a +7 oxidation state to a +6 state?
4. What does this mean in terms of electron loss/gain?
5. Who is losing electrons if manganese is gaining them? (Look at reaction in well plate #2)
6. What is the only reaction that produces an oxidation of Manganese?
7. Summarize what you learned about:
a.- Manganese in respect to oxidation and reduction.
b.- What color can tell you regarding oxidation and reduction.