1. Pg 646 - 651

2. Balancing Redox Reaction  Can use “old” way: Ag (s) + Fe(NO3)3 (aq)  Fe (s) + AgNO3 (aq)  But what if we have a reaction that looks like this…. MnO4- (aq) + Fe2+ (aq) Fe3+ (aq) + Mn2+ (aq) acid

3. Half-Reaction Method 1. Separate the reaction into an oxidation half- reaction and a reduction half-reaction. 2. Balance ANY atom that isn’t an H or O in each reaction using coefficients.

4. Half-Reaction Method 3. Balance any O’s by adding water to the opposite side of the half-reaction. 4. Balance any H’s by adding H + to the opposite side of the reaction.

5. Half-Reaction Method 5. Add electrons to each half-reaction so that the charges on both sides of the reaction are the same. 6. Balance the total number of electrons so they are EQUAL in both reactions.

6. Half-Reaction Method 7. Add the two half-reactions together 8. Check to make sure the atoms and charges balance!!

7. Let’s try one more!!  Balance the following redox reaction using the half-reaction method: Pb (s) + PbO2 (s) + H + (aq)  Pb 2+ (aq) + H2O (l)

8. Now you try one!! Balance the following reaction using the half- reaction method: Ni (s) + NO3 - (aq)  Ni 2+ (aq) + NO2 (g)