1. Electrochemistry Lesson 6 Balancing Redox Reactions

2. Balancing Redox Full Reactions in Acid Solution

3. MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2-

4. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- 1.Separate into half reactions.

5. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- 1.Separate into half reactions. 2.Balance each half reaction.

6. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- MnO 4 - →MnO 2 C 2 O 4 2- →CO 3 2- 1.Separate into half reactions. 2.Balance each half reaction.

7. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- MnO 4 - →MnO 2 C 2 O 4 2- →2CO 3 2- 1.Separate into half reactions. 2.Balance each half reaction.

8. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- MnO 4 - →MnO 2 + 2H 2 O C 2 O 4 2- →2CO 3 2- 1.Separate into half reactions. 2.Balance each half reaction.

9. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- MnO 4 - →MnO 2 + 2H 2 O C 2 O 4 2- + 2H 2 O →2CO 3 2- 1.Separate into half reactions. 2.Balance each half reaction.

10. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- MnO 4 - + 4H + →MnO 2 + 2H 2 O C 2 O 4 2- + 2H 2 O →2CO 3 2- 1.Separate into half reactions. 2.Balance each half reaction.

11. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- MnO 4 - + 4H + →MnO 2 + 2H 2 O C 2 O 4 2- + 2H 2 O →2CO 3 2- + 4H + 1.Separate into half reactions. 2.Balance each half reaction.

12. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- MnO 4 - + 4H + + 3e - →MnO 2 + 2H 2 O C 2 O 4 2- + 2H 2 O →2CO 3 2- + 4H + 1.Separate into half reactions. 2.Balance each half reaction.

13. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- MnO 4 - + 4H + + 3e - →MnO 2 + 2H 2 O C 2 O 4 2- + 2H 2 O →2CO 3 2- + 4H + + 2e - 1.Separate into half reactions. 2.Balance each half reaction.

14. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- MnO 4 - + 4H + + 3e - →MnO 2 + 2H 2 O C 2 O 4 2- + 2H 2 O →2CO 3 2- + 4H + + 2e - 1.Separate into half reactions. 2.Balance each half reaction. 3.Add the two half reactions.

15. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- 2(MnO 4 - + 4H + + 3e - →MnO 2 + 2H 2 O) 3(C 2 O 4 2- + 2H 2 O →2CO 3 2- + 4H + + 2e - ) 1.Separate into half reactions. 2.Balance each half reaction. 3.Add the two half reactions.

16. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- 2(MnO 4 - + 4H + + 3e - →MnO 2 + 2H 2 O) 3(C 2 O 4 2- + 2H 2 O →2CO 3 2- + 4H + + 2e - ) 2MnO 4 - + 8H + + 3C 2 O 4 2- + 6H 2 O→ 2MnO 2 + 4H 2 O + 6CO 3 2- + 12H + 1.Separate into half reactions. 2.Balance each half reaction. 3.Add the two half reactions.

17. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- 2(MnO 4 - + 4H + + 3e - →MnO 2 + 2H 2 O) 3(C 2 O 4 2- + 2H 2 O →2CO 3 2- + 4H + + 2e - ) 2MnO 4 - + 8H + + 3C 2 O 4 2- + 6H 2 O→ 2MnO 2 + 4H 2 O + 6CO 3 2- + 12H + 1.Separate into half reactions. 2.Balance each half reaction. 3.Add the two half reactions. 4.Simplify

18. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- 2(MnO 4 - + 4H + + 3e - →MnO 2 + 2H 2 O) 3(C 2 O 4 2- + 2H 2 O →2CO 3 2- + 4H + + 2e - ) 24 2MnO 4 - + 8H + + 3C 2 O 4 2- + 6H 2 O→ 2MnO 2 + 4H 2 O + 6CO 3 2- + 12H + 1.Separate into half reactions. 2.Balance each half reaction. 3.Add the two half reactions. 4.Simplify

19. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- 2(MnO 4 - + 4H + + 3e - →MnO 2 + 2H 2 O) 3(C 2 O 4 2- + 2H 2 O →2CO 3 2- + 4H + + 2e - ) 2MnO 4 - + 3C 2 O 4 2- + 2H 2 O→ 2MnO 2 + 6CO 3 2- + 4H + 1.Separate into half reactions. 2.Balance each half reaction. 3.Add the two half reactions. 4.Simplify

20. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- 2(MnO 4 - + 4H + + 3e - →MnO 2 + 2H 2 O) 3(C 2 O 4 2- + 2H 2 O →2CO 3 2- + 4H + + 2e - ) 2MnO 4 - + 3C 2 O 4 2- + 2H 2 O→ 2MnO 2 + 6CO 3 2- + 4H + 1.Separate into half reactions. 2.Balance each half reaction. 3.Add the two half reactions. 4.Simplify 5.Check

21. Balancing Redox Full Reactions in Acid Solution MnO 4 - + C 2 O 4 2- →MnO 2 + CO 3 2- 2(MnO 4 - + 4H + + 3e - →MnO 2 + 2H 2 O) 3(C 2 O 4 2- + 2H 2 O →2CO 3 2- + 4H + + 2e - ) -8-8 2MnO 4 - + 3C 2 O 4 2- + 2H 2 O→ 2MnO 2 + 6CO 3 2- + 4H + 1.Separate into half reactions. 2.Balance each half reaction. 3.Add the two half reactions. 4.Simplify 5.Check

22. Balancing Redox Full Reactions in Basic Solution 2MnO 4 - + 3C 2 O 4 2- + 2H 2 O→ 2MnO 2 + 6CO 3 2- + 4H +

23. Balancing Redox Full Reactions in Basic Solution 2MnO 4 - + 3C 2 O 4 2- + 2H 2 O→ 2MnO 2 + 6CO 3 2- + 4H + 1.Balance in acid solution

24. Balancing Redox Full Reactions in Basic Solution 2MnO 4 - + 3C 2 O 4 2- + 2H 2 O→ 2MnO 2 + 6CO 3 2- + 4H + 1.Balance in acid solution 2.Add OH - to neutralize the H +

25. Balancing Redox Full Reactions in Basic Solution 2MnO 4 - + 3C 2 O 4 2- + 2H 2 O→ 2MnO 2 + 6CO 3 2- + 4H + 4OH - 4OH - 1.Balance in acid solution 2.Add OH - to neutralize the H + 3.Simplify

26. Balancing Redox Full Reactions in Basic Solution 2MnO 4 - + 3C 2 O 4 2- + 2H 2 O→ 2MnO 2 + 6CO 3 2- + 4H + 4OH - 4OH - 4H 2 O 1.Balance in acid solution 2.Add OH - to neutralize the H + 3.Simplify

27. Balancing Redox Full Reactions in Basic Solution 2MnO 4 - + 3C 2 O 4 2- + 4OH - → 2MnO 2 + 6CO 3 2- + 2H 2 O 1.Balance in acid solution 2.Add OH - to neutralize the H + 3.Simplify

28. Balancing Redox Full Reactions in Basic Solution 2MnO 4 - + 3C 2 O 4 2- + 4OH - → 2MnO 2 + 6CO 3 2- + 2H 2 O 1.Balance in acid solution 2.Add OH - to neutralize the H + 3.Simplify 4.Check

29. Balancing Redox Full Reactions in Basic Solution 2MnO 4 - + 3C 2 O 4 2- + 4OH - → 2MnO 2 + 6CO 3 2- + 2H 2 O 1.Balance in acid solution 2.Add OH - to neutralize the H + 3.Simplify 4.Check

30. Balancing Redox Full Reactions in Basic Solution 2MnO 4 - + 3C 2 O 4 2- + 4OH - → 2MnO 2 + 6CO 3 2- + 2H 2 O-12 1.Balance in acid solution 2.Add OH - to neutralize the H + 3.Simplify 4.Check

31. Balancing Redox Full Reactions in Basic Solution Fe+O 2 → H 2 O+Fe(OH) 2

32. Balancing Redox Full Reactions in Basic Solution Fe→Fe(OH) 2 O 2 → H 2 O

33. Balancing Redox Full Reactions in Basic Solution Fe +2H 2 O→Fe(OH) 2 O 2 → H 2 O + H 2 O

34. Balancing Redox Full Reactions in Basic Solution Fe +2H 2 O→2H + +Fe(OH) 2 O 2 +4H + → H 2 O + H 2 O

35. Balancing Redox Full Reactions in Basic Solution Fe +2H 2 O→2H + +Fe(OH) 2 + 2e - 4e - + O 2 +4H + → H 2 O + H 2 O

36. Balancing Redox Full Reactions in Basic Solution 2(Fe +2H 2 O→2H + +Fe(OH) 2 + 2e - ) 4e - + O 2 +4H + → H 2 O + H 2 O

37. Balancing Redox Full Reactions in Basic Solution 2(Fe +2H 2 O→2H + +Fe(OH) 2 + 2e - ) 4e - + O 2 +4H + → H 2 O + H 2 O 2Fe + 4H 2 O + O 2 +4H + → 4H + + 2Fe(OH) 2 + 2H 2 O

38. Balancing Redox Full Reactions in Basic Solution 2(Fe +2H 2 O→2H + +Fe(OH) 2 + 2e - ) 4e - + O 2 +4H + → H 2 O + H 2 O 2 2Fe + 4H 2 O + O 2 +4H + → 4H + + 2Fe(OH) 2 + 2H 2 O

39. Balancing Redox Full Reactions in Basic Solution 2(Fe +2H 2 O→2H + +Fe(OH) 2 + 2e - ) 4e - + O 2 +4H + → H 2 O + H 2 O 2 2Fe + 4H 2 O + O 2 + 4H + → 4H + + 2Fe(OH) 2 + 2H 2 O 2Fe + 2H 2 O + O 2 → 2Fe(OH) 2

40. Balancing Redox Full Reactions in Basic Solution 2(Fe +2H 2 O→2H + +Fe(OH) 2 + 2e - ) 4e - + O 2 +4H + → H 2 O + H 2 O 2Fe + 2H 2 O + O 2 → 2Fe(OH) 2 No need to add OH -

41. As→H 2 AsO 4 - +AsH 3 (alkaline) 3(As+ 4H 2 O→H 2 AsO 4 - +6H + + 5e - ) 5(3H + +As+ 3e - →AsH 3 ) 3As + 12H 2 O + 15H + + 5As → 3H 2 AsO 4 - + 18H + + 5AsH 3 8As + 12H 2 O → 3H 2 AsO 4 - + 3H + + 5AsH 3 3OH - 3OH - + 8As + 9H 2 O → 3H 2 AsO 4 - + 5AsH 3-3