Sulfuric acid is corrosive and toxic
Sodium hydroxide is caustic
Chemicals and Solutions:
Note: A convenient way to display the various oxidation states of manganese is to use petri dishes or beakers on an overhead projector.
Mn+2 FAINT PINK TO COLORLES
Dissolve 12 grams of MnSO4in 100 ml 3M H2SO4
Acidify 50 ml of the Mn+2 solution above with 10 ml conc. H2SO4 and add 1-2 ml of 0.01 M KMnO4
Continue adding the 0.01M KMnO4 to the Mn+3 solution.
(Brown color will become more obvious with addition of distilled H2O.)
Acidify the Mn+6 solution produced below with 3MH2SO4 until the brown color develops.
Place about 10 or 15 solid KOH pellets on a petri dish and add 1-2 ml of 0.01M KMnO4 and stir for about 1-2 minutes until the blue color of the Mn+5 appears. On standing the color will change to the green of Mn+6 The blue Mn+5 can be regenerated by adding a few drops of the 0.01M KMnO4 and stirring. Addition of distilled water to the +5 mixture will increase the length of time the color persists.
Dilute the 0.01M KMnO4 about 100 fold with distilled water and add 2 ml of 1M NaOH to 25 ml of the diluted solution. Add 0.01M Na2SO3 dropwise with constant stirring until the green color of Mn+6 appears.
Add 10 grams of solid MnO2 to a filter cone. Pour about 50 ml of strongly basic 0.01M KMnO4 through the cone. The filtrate will contain the green Mn+6
Dissolve 1.58 grams of KMnO4 in one liter of distilled water to make a 0.01M solution.