Ch 18.1 Balancing
Oxidation-Reduction
Equations
Luckett
AP Chemistry
Electrochemistry Definition
 The
study of the interchange of
chemical and electrical energy.
 Involve oxidation-reduction reactions
Half-Reaction Method
 Used
to balance redox rxns in aqueous
solution
 One of the rxns is the oxidation rxn
 Other is the reduction rxn
 The half reactions are balanced separately
and then added
 Differs in acidic vs. basic solution
In Acidic Solution
1.
2.
3.
4.
5.
Separate the oxid. and red. parts of the rxn.
For each:
a. Balance all elements but H and O
b. Balance O using H2O
c. Balance H using H+
d. Balance charge using electrons
If needed, mult. One or both half-rxns. by a
whole # to make electrons equal for both
Add half-rxns and cancel same on both sides
Make sure elements/charges are balanced
Acronym for Balancing in Acid
 Big
B
White Hogs Eat Bagels and Cream Cheese
= balance all but H & O
 W = add water for O’s
 H = Add H
 E = Add electrons
 B = Make sure electrons match
 CC = Combine and cancel
In Basic Solution
 Follow
the steps used in acidic solution
THEN…
 Add OH- to match H+ on same side. Add to
other side as well
 Form H2O by adding OH- and H+
 Cancel H2O’s on both sides
 Check for element/charge balance
Example in Acid
Example in Base