1. Day 2: Balancing Redox Reactions in Acidic or Basic solutions

2. Review Redox Balancing:
Steps:
Write half rxn’s
Balance atoms
Balance electrons
Add the half rxn’s
Review Redox Balancing:
Balance the following chemical equation using the half reaction method
Easy: __Fe(s) + __Ag+  __Fe __Ag(s)
Hard: __NH3 + __O2  __NO + __H2O

3. Balancing Redox Rxns in Acid/Alkaline Solution
Some redox rxns occur in solutions that are acidic or basic, so H2O, H+ , and OH- are also involved in the reactions
For acid soln
Steps:
Write half rxn’s
Balance atoms
Balance electrons
Add the half rxn’s
2a. Add H2O to balance the O’s
2b. Add H+ to balance the H’s
2c. Add OH- to both sides of the rxn for each H used
For base soln

4. Example:
The following reaction takes place in an acidic solution. Balance it.
VO2+1 (aq) + Zn(s)  VO2+ (aq) + Zn2+ (aq)

5. Example:
The following reaction takes place in a basic solution. Balance it.
Al(s) + S(s)  Al(OH)3(s) + HS- (aq)

6. Steps: Write half rxn’s Balance atoms Balance electrons
Add the half rxn’s