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Electrochemistry Lesson 3 Oxidation Numbers

Learn about assigning oxidation numbers to determine oxidation/reduction reactions, rules & examples for various elements and compounds. Practice identifying oxidizing and reducing agents.

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Electrochemistry Lesson 3 Oxidation Numbers

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  1. Electrochemistry Lesson 3 Oxidation Numbers

  2. Ho Ho Ho Silver crystals on a copper frame

  3. Oxidation Numbers HV2O4- V6+ Is the above equation oxidation or reduction? Oxidation numbersare assigned numbers that are used to determine if oxidation or reduction has occurred.

  4. Rules for Oxidation NumbersOxidation # 1. All elements are zero: N2 0 Pb 0 Na 0 O2 0

  5. Rules for Oxidation NumbersOxidation # 2. Monatomic Ions are their charge Na+ +1 -1 Br- +2 MgSO4 -2 Al2S3

  6. Rules for Oxidation NumbersOxidation # 3. O in a compound is -2 exception: peroxides-1 Na2O -2 CO2 -2 O2 0 CH3COOH -2 -1 exception HOOH

  7. Rules for Oxidation NumbersOxidation # 4. H in a compound is +1 exception:metal hydrides-1 H2O +1 +1 C12H22O11 0 H2 -1 NaH

  8. Rules for Oxidation Numbers 5. The sum of the oxidation numbersmust equal the charge oxidation #s SO42- Total charge +6 -2 -2 x 4 +6 -8 = -2

  9. oxidation #s PO43- Total charge +5 -2 +5 -8 = -3

  10. oxidation #s Cr2O72- Total charge +6 -2 12 / 2 +12 -14 = -2

  11. Ca(NO3)2 +2

  12. Na2C4O8 +1 +7/2 -2 +2 +14 -16 = 0

  13. CH3COOH

  14. Rewrite C2H4O2 0 +1 -2 0 +4 -4 = 0

  15. Zn(OH)42- +2 -2 +1 +2 -8 +4 = -2

  16. H2PtCl6 +1 +4 -1 +2 +4 -6 = 0

  17. H3PO3 +1 +3 -2 +3 +3 -6 = 0

  18. Al(NO3)3 +3 +5 -2 +3 +15 -18 = 0

  19. Na2O2 Exception - does not work, O must be -1 +1 -2 -1 +2 -4 -2 = 0

  20. CaH2 +2 +1 -1 +2 +2 -2 = 0 Exception - does not work, H must be -1

  21. Fe(H2O)5(OH)2+

  22. 0-1 Fe(H2O)5(OH)2+? +0-1 = +2

  23. +30-1 Fe(H2O)5(OH)2++3 +0-1 = +2

  24. Oxidation Numbers HV2O4- V6+ Is the above equation oxidation or reduction? Increase +6 +3 If the oxidation number increases it is oxidation.

  25. Using Oxidation Numbers If the oxidation number of the central atomincreases going from left to right, its oxidation. ClO2-ClO4- Increase is oxidation +3 +7 oxidation reducing agent 4 electronslost

  26. Using Oxidation Numbers If the oxidation number of the central atomdecreases going from left to right, its reduction. NO3- HNO2 +5 +3 decrease is reduction reduction 2 electronsgained oxidizing agent

  27. Label the oxidizing agent and the reducing agent. +7+1+50 ReO4- + IO-  IO3- + Re Reduced Oxidized Ox Agent Red Agent

  28. Label the oxidizing agent and the reducing agent. +3+5 +5 +2 3As2O3 + 4NO3- + 7H2O + 4H+6H3AsO4 + 4NO oxidized reduced red agent ox agent Numa Numa

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