Chemistry question, KMnO4 redox.

Question

KMnO4 is an oxidizer that goes from purple KMnO4 to colorless Mn 2 , when the reaction is done in an acid environment.

Is this always true or can it turn to MnO2, as i have two different balanced equations both from very good chemists. One balanced a chemical equation between KMnO4 C2H2O4 H2 and the other KMnO4 C2H2O4 H2SO4. Is this what makes the difference or has one made a mistake. Also could you explain why this is the case? or if it is easeir answer the original question i was trying to answer which is.given the half equation for the oxidation of oxalic acid under acidic conditions is.

C2H2O4 ---------> 2CO2 2H 2e-

Write a balanced equation for the reaction between KMnO4 and C2H2O4.

It would help me out so much to get an aswer, and be very much appreciated sorry about asking so much in one question but i really am confused.

Answer 1

It only goes to MnO2 in a basic solution.  In acidic solution it goes to Mn2+.

There is no "KMnO4 C2H2O4 H2", I would guess that he meant to write "KMnO4 C2H2O4 H2O", but that would still not give Mn2+.  Even if you started with some H2SO4 and it was not enough you would still get MnO2 being formed.

Think about it.  If permanganate is reacting with oxalic ACID, then the solution should be acidic!!!  You can't have a basic oxalic acid solution.  (But the products can be basic if all of the oxalic acid is neutralized.)

2( 8H+ + MnO4- + 5e-  --> Mn2+ + 4H2O )

5( H2C2O4  -->  2CO2 + 2H+ + 2e- )

--------------------------------------...

16H+ + 2MnO4- + 5H2C2O4 --> 2Mn2+ + 10CO2 + 8H2O + 10H+

simplify

6H+  + 2MnO4- + 5H2C2O4 --> 2Mn2+ + 10CO2 + 8H2O

As you can see even more H+ is needed.  This would be one of those cases where all of the oxalic acid would be neutralized to give a basic product along with MnO2.  Therefore, additional acid is needed to keep the solution acidic.

Answer 2

when we do this reaction: KMnO4 and C2H2O4.

we do it in an acid environment (additional H2SO4),

under these conditions KMnO4 goes to Mn+2.

going fomm pink /purlple  to colorless is an advantage in titrations.

when a person does not do it in an acidic enough solution , that's the one that gives the less-desireable -for-titration reaction that produces the brown precipitate MnO2.

your equation should be :

2 KMnO4  & 5 H2C2O4 &3 H2SO4 --> K2SO4 & 2MnSO4 & 10 CO2 & 8 H2O