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-   -   Balancing redox reactions occurring in acidic solutions (http://www.physicsforums.com/showthread.php?t=357764)

shikam08 Nov24-09 06:13 PM

Balancing redox reactions occurring in acidic solutions
 
1. The problem statement, all variables and given/known data
Balance the following redox reactions occurring in an acidic solution.


2. Relevant equations
PbO2(s)+I-(aq)---->Pb2+(aq)+I2(s)


3. The attempt at a solution
1.) half reactions:
a.) reduction: I-(aq)----->I2(s)
b.) oxidation: PbO2(s)------>Pb2+(aq)
2.) balance Oxygens and Hydrogens
PbO2+4H+------>Pb2++2H2O
3.) add electrons to balance equations
a.)PbO2+4H++4e---->Pb+2+2H2O
b.) 4I--->4I2+4e-
4.) cancel out the electrons and combine the half reactions
PbO2+4H++4I--->Pb2++4I2+2H2O

Borek Nov25-09 02:13 AM

Re: Balancing redox reactions occurring in acidic solutions
 
Quote:

Quote by shikam08 (Post 2458269)
b.) 4I--->4I2+4e-

Nope.

shikam08 Nov29-09 08:31 PM

Re: Balancing redox reactions occurring in acidic solutions
 
I don't understand how to insert the number of electrons on both sides to balance the equations and cancel out the electrons.

Borek Nov30-09 02:27 AM

Re: Balancing redox reactions occurring in acidic solutions
 
Balance atoms first, then use electrons to balance charge in half reaction. As long as charge on both sides is different, equation is not balanced.


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