Oxidation States of Manganese For each test tube - #3, #4 and #5 - record the fo

Question

Oxidation States of Manganese

For each test tube - #3, #4 and #5 - record the following results of the reactions:

2. Based on these results, to what oxidation states did the Mn change in each test tube?

3. Write the net ionic equations for the redox reactions in each test tube:
Referring to the table in the background of the lab manual may be helpful.

Need help with #3

Here is the rough procedure

First we obtained 5 test tube, We filled the first test tube with 5Ml of water, the second with 5mL of 0.02M Potassium Permanganate , and the third, fourth, and fifth with 9mL of the potassium Permanganate.

Next we added 1mL of 2m sodium hydroxide to test tube 3 and 1mL of 3m sulfuric acid to test tube 5. We then recorded the pH of all the test tubes

1: 7

2: 7

3: 14

4: 7

5: 1.27

Next, we aquired a beaker and a dropper and added 20mL of 0.1M sodium bisulfite to the beaker

Two drops of Sodium bisulfite at a time added to test tube 3

The test tube3, turned green as compated to the first test tube ...oxidation state +6

In Test tube 4, The color changed to clear as water and a black solid formation occured .. oxidation state +4

In test tube 5, the solution turned a pale pink indicating an oxidation state of +2

Tube #3 Tube #4 Tube #5 a Color of the solution
   Green Clear
   Pale Pink b Color of the precipitate, if any black
  

Explanation / Answer

the reaction between NaOH and Potassium Permanganate

KMnO4+2NaOH=2KOH+2Na2O+MnO2 so here Mn is in +4 state.

after adding sodium bisuphite

2 NaHSO3 + 2 NaOH + 2 KMnO4 => 2 Na2SO4 + 2 KOH + 2 MnO2 + 1/2 O2 + H2O

There is an acidic salt, a base and an oxidizer. The acidic salt and the base will give a salt and water. Then the oxidizer has to oxidize something. That would be the Sodium thiosulfate to Sodium sulfate. That will "consume" the water from the reaction between the acidic salt and the base and it will give the second part of the reaction. The trick is to let the acidic salt to react with the base first and then take the results and put them in reaction with the KMnO4. But in the final result you are not going to include the intermediate "imaginary" reaction which is 2 Na2SO3 + 2 H2O + 2 KMnO4.

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