L1 /
11
CH1012
BALANCING REDOX EQNS II
Balancing a redox
rxn in Acidic Solution
1) Split the reaction into 2 half reactions.
2) Balance the heavy atoms in each half rxn.
3) Add water
molecule(s) to balance oxygen
to each half rxn as appropriate.
to each half rxn as appropriate.
4) Add H+ to balance H in each half rxn.
5) Add electrons to each half rxn, add to the
side which has the more positive charge
to equal the charge on the other side.
side which has the more positive charge
to equal the charge on the other side.
6) Balance the number
of electrons across
both half reactions (same no of e- in both)
both half reactions (same no of e- in both)
7) Add both half
reactions together,
cancelling common things (H+, H2O, e-)
cancelling common things (H+, H2O, e-)
8) Do an atom balance LHS = RHS.
Cr2O72-(aq + Fe2+(aq ® Cr3+(aq + Fe3+(aq
