Electrochemistry Lesson 6 Balancing Redox Reactions

Balancing Redox Full Reactions in Acid Solution MnO4- + C2O42- → MnO2 + CO32- MnO4- → MnO2 C2O42- → CO32- 2MnO4- + 3C2O42- + 6H2O + 8H+ → 2MnO2 + 6CO32- + 12H+ + 4H2O 2MnO4- + 3C2O42- + 2H2O → 2MnO2 + 6CO32- + 4H+ 4. Simplify 3. Add the two half reactions 5. Check 2. Balance each half reaction 1. Separate into half reactions 2( + 4H+ + 3e- + 2H2O ) 3( + 2H2O 2 + 4H+ + 2e- ) 2 4 -8 -8

Balancing Redox Full Reactions in Basic Solution 2MnO4- + 3C2O42- + 2H2O → 2MnO2 + 6CO32- + 4H+ 2. Add OH- to neutralize the H+ 1. Balance in acid solution 4OH- 4OH- 2 4H2O

Balancing Redox Full Reactions in Basic Solution 2MnO4- + 3C2O42- + → 2MnO2 + 6CO32- + -12 -12 4OH- 2H2O

Balancing Redox Full Reactions in Acid Solution Fe + O2 → H2O + Fe(OH)3 Fe + → + Fe(OH)3 O2 → H20 4Fe + 12H2O + 3O2 +12H+ → 12H+ + 4Fe(OH)3 + 6H2O 4Fe + 6H2O + 3O2 → 4Fe(OH)3 4( 3H2O 3H+ + 3e -) 3( 4e- + + 4H+ + H2O) 6

Balance the redox reaction As → H2AsO4- + AsH3 (alkaline) You must separate into two half reactions! 3As + 12H2O + 15H+ + 5As → 3H2AsO4- + 18H+ + 5AsH3 8As + 12H2O → 3H2AsO4- + 3H+ + 5AsH3 3OH- 3OH- 3OH- + 8As + 9H2O → 3H2AsO4- + 5AsH3 -3 -3 3( As + 4H2O → H2AsO4- + 6H+ + 5e- ) 5( ) 3H+ + As + 3e- → AsH3 3

Balance the redox reaction IPO4- → IO3- + I2 + PO43- (alkaline) You must separate into two half reactions!

Balance the redox reaction IPO4- → IO3- + I2 + PO43- (alkaline) You must separate into two half reactions! IPO4- → + PO43-

Balance the redox reaction IPO4- → IO3- + I2 + PO43- (alkaline) You must separate into two half reactions! IPO4- → + PO43- IPO4- → + PO43-

Balance the redox reaction IPO4- → IO3- + I2 + PO43- (alkaline) You must separate into two half reactions! IPO4- → IO3- + PO43- IPO4- → I2 + PO43-

Balance the redox reaction IPO4- → IO3- + I2 + PO43- (alkaline) You must separate into two half reactions! IPO4- → IO3- + PO43- 2IPO4- → I2 + 2PO43-

Balance the redox reaction IPO4- → IO3- + I2 + PO43- (alkaline) You must separate into two half reactions! IPO4- + 3H2O → IO3- + PO43- + 6H+ 2IPO4- → I2 + 2PO43-

Balance the redox reaction IPO4- → IO3- + I2 + PO43- (alkaline) You must separate into two half reactions! IPO4- + 3H2O → IO3- + PO43- + 6H+ + 3e- 2IPO4- + 4e- → I2 + 2PO43-

Balance the redox reaction IPO4- → IO3- + I2 + PO43- (alkaline) You must separate into two half reactions! 4(IPO4- + 3H2O → IO3- + PO43- + 6H+ + 3e-) 3(2IPO4- + 4e- → I2 + 2PO43-)

Balance the redox reaction IPO4- → IO3- + I2 + PO43- (alkaline) You must separate into two half reactions! 4(IPO4- + 3H2O → IO3- + PO43- + 6H+ + 3e-) 3(2IPO4- + 4e- → I2 + 2PO43-) 12H2O + 10IPO4- → 3I2 + 10PO43- + 24H+ + 4IO3- 24OH- 24OH- 24OH- + 10IPO4- → 3I2 + 10PO43- + 4IO3- + 12H2O -34 -34 Fast Food Rap