Chem. Half-Reactions

1. Oct 25, 2007

DumbDuck

Problem:
Determine concentration of H2O2 with Titration of KMnO4

Balance the equation and create a net ionic equation then balance using redox techniques and replace spectator ions

Balanced Equation:
5H2O2 + 2KMnO4 + H2SO4 ==> K2SO4 + MnSO4 + H2O + O2

My Work:
I eliminated all spectators and my net ionic equation was

16H(+) + 18O(2-) ==> 8H20 + 5O2

This cannot be correct, since putting this into a half-reaction

8H2O + 16H(+) ==> 8H2O + 16H(+) there is no need for e- and therefore is not a redox reaction. If I have the correct ionic equation I'm sure I can figure out the rest

2. Oct 26, 2007

chemisttree

Half reactions are reactions where the oxidant's reaction is shown separately from the reductant's reaction. It can be generalized as:

[O] + e- ----> [O]- ( or [O]+ + e- ------> [O] )

and

[R] -------> [R]+ + e- ( or [R]- ------> [R] + e- )

where [O] is the oxidant and [R] is the reductant.

In your example what is the reductant and the oxidant? Hint: H+ is neither...