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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: ikariotis on June 03, 2010, 05:17:35 PM

Title: How to balance organic ox-red reaction
Post by: ikariotis on June 03, 2010, 05:17:35 PM
Hey!

Please help me balance following formula

C7H5NO3 + KMnO4  :rarrow: C7H5NO4

Ox: .
Red: ...

Total: .

No representation of electron-es in the total reaction.
Title: Re: How to balance organic ox-red reaction
Post by: Jorriss on June 04, 2010, 12:22:46 AM
Where's your Manganese in the products?
Title: Re: How to balance organic ox-red reaction
Post by: Borek on June 04, 2010, 04:10:14 AM
Obviously this is just a scheme that has to be filled up with lacking substances.

First of all - do you know what are conditions (acidic, neutral, basic) of the reaction?
Title: Re: How to balance organic ox-red reaction
Post by: ikariotis on June 04, 2010, 05:59:19 AM
the problem is just an oxidation whitout any conditions, but we have to do an redoxreaction scheme.

My example

Ox: MnO4- + 4H+ + 3e-  :rarrow: MnO2 + 2H2O
Red: C7H5NO3 + H2O  :rarrow: C7H5NO4 + 2H+ + 2e-

When I do like this I am gonna have electron-es on my total reaction so how can I eliminate this problem and still balance the reaction?
Title: Re: How to balance organic ox-red reaction
Post by: Schrödinger on June 04, 2010, 07:15:09 AM
If you want to eliminate the electrons, then multiply each reaction by suitable factors (Least Common Multiple LCM) that will make the number of electrons equal in both the half reactions.  Then just add the reactions.
Title: Re: How to balance organic ox-red reaction
Post by: Borek on June 04, 2010, 11:40:50 AM
Quote from: ikariotis on June 04, 2010, 05:59:19 AM
the problem is just an oxidation whitout any conditions

So it can't be done, as products of permanganate reduction depend on the pH.


Quote
Ox: MnO4- + 4H+ + 3e-  :rarrow: MnO2 + 2H2O
Red: C7H5NO3 + H2O  :rarrow: C7H5NO4 + 2H+ + 2e-

You got Red & Ox reversed.
Title: Re: How to balance organic ox-red reaction
Post by: Schrödinger on June 04, 2010, 01:56:20 PM
Quote from: Borek on June 04, 2010, 11:40:50 AM
Quote
Ox: MnO4- + 4H+ + 3e-  :rarrow: MnO2 + 2H2O
Red: C7H5NO3 + H2O  :rarrow: C7H5NO4 + 2H+ + 2e-

You got Red & Ox reversed.
I didn't notice that   :-[