posted by Joanne .
Balance the equation in aqueous basic solution:
As2S3(s) + H2O2(aq) → AsO43-(aq) + SO42-(aq)
I normally understand how to balance redox equations, but this one confuses me because I would normally think that the As2S3 is being reduced to AsO4^3-, but since the As2S3 has a "S", do i also include the SO4^2-? but even when i do that, and try to balance the electrons for the half rxn, it seems to change into oxidation... I'm really confused!
I usually attack this type this way. Yes, both As and S are changing, As from +6(total of 2 atoms As) to +10(total of 2 atoms As). S is changing from -6 (total of 3 S atoms to +18(total of 3 atoms S). Most of the time it works out if one simply combines the As and S into one kind of reaction (add electrons algebraically). What has been omitted is the reaction of the H2O2. You'll see what to do when that is included.