CH1012
L1 /
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L1 /
11
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
