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Electrochemistry Lesson 3 Oxidation Numbers. Ho Ho Ho. Silver crystals on a copper frame. Oxidation Numbers HV 2 O 4 - V 6+ Is the above equation oxidation or reduction? Oxidation numbers are assigned numbers that are used to determine if oxidation or reduction has occurred.
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Electrochemistry Lesson 3 Oxidation Numbers
Ho Ho Ho Silver crystals on a copper frame
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.
Rules for Oxidation NumbersOxidation # 1. All elements are zero: N2 0 Pb 0 Na 0 O2 0
Rules for Oxidation NumbersOxidation # 2. Monatomic Ions are their charge Na+ +1 -1 Br- +2 MgSO4 -2 Al2S3
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
Rules for Oxidation NumbersOxidation # 4. H in a compound is +1 exception:metal hydrides-1 H2O +1 +1 C12H22O11 0 H2 -1 NaH
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
oxidation #s PO43- Total charge +5 -2 +5 -8 = -3
oxidation #s Cr2O72- Total charge +6 -2 12 / 2 +12 -14 = -2
Ca(NO3)2 +2
Na2C4O8 +1 +7/2 -2 +2 +14 -16 = 0
Rewrite C2H4O2 0 +1 -2 0 +4 -4 = 0
Zn(OH)42- +2 -2 +1 +2 -8 +4 = -2
H2PtCl6 +1 +4 -1 +2 +4 -6 = 0
H3PO3 +1 +3 -2 +3 +3 -6 = 0
Al(NO3)3 +3 +5 -2 +3 +15 -18 = 0
Na2O2 Exception - does not work, O must be -1 +1 -2 -1 +2 -4 -2 = 0
CaH2 +2 +1 -1 +2 +2 -2 = 0 Exception - does not work, H must be -1
0-1 Fe(H2O)5(OH)2+? +0-1 = +2
+30-1 Fe(H2O)5(OH)2++3 +0-1 = +2
Oxidation Numbers HV2O4- V6+ Is the above equation oxidation or reduction? Increase +6 +3 If the oxidation number increases it is oxidation.
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
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
Label the oxidizing agent and the reducing agent. +7+1+50 ReO4- + IO- IO3- + Re Reduced Oxidized Ox Agent Red Agent
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