Solving Half Equation Problems in Redox Reactions

[fabbo]

I find it really hard to write half equations from the given redox reaction. I'm ok when H+ and water are not involved but when they are I get stuck.

Eg. for this reaction:

IO3- + 5I- + 6H+ ----------> 3I2 + 3H2O

How would you go about splitting it up as I features as a reactant twice?

 

[Vagrant]

u could try these steps-
separate oxidation n reduction 1/2 reactions
balance atms other than Oxygen n water
balance H in acidic med. by adding H+ n in basic med. by adding equal no of water molecules,(ie 2H --> 2H2O) n equal no of OH- to the other side
balance charges by adding electrons
Add the two balanced reactions in such a way that the electrons are eliminated frm the reaction.

For splitting Find oxidation no of all the I containing species. oxidation takes place if it inc frm rectant to product side otherwise its reduction

 

[Borek]

Start with

IO3- -> 1/2 I2

I- -> 1/2 I2

Whatever will be in excess, will finally cancel out, or you will end with coefficients to simplify - both cases easy to deal with.