Oxidation Numbers 

HV2O4- V6+

 Is the above equation oxidation or reduction?

Oxidation numbers are used to quickly determine if oxidation or reduction has occurred in a redox reaction.

Rules for Oxidation Numbers Oxidation # 1. All elements are zero:

Rules for Oxidation Numbers Oxidation # 1. All elements are zero:

N2

Rules for Oxidation Numbers Oxidation # 1. All elements are zero:

N2 0

Rules for Oxidation Numbers Oxidation # 1. All elements are zero:

N2 0

Pb

Rules for Oxidation Numbers Oxidation # 1. All elements are zero:

N2 0

Pb 0

Rules for Oxidation Numbers Oxidation # 1. All elements are zero:

N2 0

Pb 0

Na

Rules for Oxidation Numbers Oxidation # 1. All elements are zero:

N2 0

Pb 0

Na 0

Rules for Oxidation Numbers Oxidation # 1. All elements are zero:

N2 0

Pb 0

Na 0

O2

Rules for Oxidation Numbers Oxidation # 1. All elements are zero:

N2 0

Pb 0

Na 0

O2 0

Rules for Oxidation Numbers Oxidation # 2. Ions are their charge

Na+

Rules for Oxidation Numbers Oxidation # 2. Ions are their charge

Na+ +1

Rules for Oxidation Numbers Oxidation # 2. Ions are their charge

Na+ +1

Br-

Rules for Oxidation Numbers Oxidation # 2. Ions are their charge

Na+ +1

Br- -1

Rules for Oxidation Numbers Oxidation # 2. Ions are their charge

Na+ +1

Br- -1

MgSO4

Rules for Oxidation Numbers Oxidation # 2. Ions are their charge

Na+ +1

Br- -1

MgSO4 +2

Rules for Oxidation Numbers Oxidation # 2. Ions are their charge

Na+ +1

Br- -1

MgSO4 +2

Al2O3

Rules for Oxidation Numbers Oxidation # 2. Ions are their charge

Na+ +1

Br- -1

MgSO4 +2

Al2O3 -2

Rules for Oxidation Numbers Oxidation # 3. The oxidation number of O

in a compound is –2. 

Na2O

Rules for Oxidation Numbers Oxidation # 3. The oxidation number of O

in a compound is –2. 

Na2O -2

Rules for Oxidation Numbers Oxidation # 3. The oxidation number of O

in a compound is –2. 

Na2O -2

CO2

Rules for Oxidation Numbers Oxidation # 3. The oxidation number of O

in a compound is –2. 

Na2O -2

CO2 -2

Rules for Oxidation Numbers Oxidation # 3. The oxidation number of O

in a compound is –2. 

Na2O -2

CO2 -2

O2

Rules for Oxidation Numbers Oxidation # 3. The oxidation number of O

in a compound is –2. 

Na2O -2

CO2 -2

O2 0

Rules for Oxidation Numbers Oxidation # 3. The oxidation number of O

in a compound is –2. 

Na2O -2

CO2 -2

O2 0

CH3COOH

Rules for Oxidation Numbers Oxidation # 3. The oxidation number of O

in a compound is –2. 

Na2O -2

CO2 -2

O2 0

CH3COOH -2

Rules for Oxidation Numbers Oxidation # 3. The oxidation number of O

in a compound is –2 or inperoxides -1.

 Na2O -2

CO2 -2

O2 0

CH3COOH -2

HOOH

Rules for Oxidation Numbers Oxidation # 3. The oxidation number of O

in a compound is –2 or inperoxides -1.

 Na2O -2

CO2 -2

O2 0

CH3COOH -2

HOOH -1

Rules for Oxidation Numbers Oxidation # 4. The oxidation number for H

in a compound is +1. 

Rules for Oxidation Numbers Oxidation # 4. The oxidation number for H

in a compound is +1. 

H2O

Rules for Oxidation Numbers Oxidation # 4. The oxidation number for H

in a compound is +1. 

H2O +1

Rules for Oxidation Numbers Oxidation # 4. The oxidation number for H

in a compound is +1 

H2O +1

C12H24O11

Rules for Oxidation Numbers Oxidation # 4. The oxidation number for H

in a compound is +1 

H2O +1

C12H24O11 +1

Rules for Oxidation Numbers Oxidation # 4. The oxidation number for H

in a compound is +1 

H2O +1

C12H24O11 +1

H2

Rules for Oxidation Numbers Oxidation # 4. The oxidation number for H

in a compound is +1 

H2O +1

C12H22O11 +1

H2 0

Rules for Oxidation Numbers Oxidation # 4. The oxidation number for H

in a compound is +1 or inmetal hydrides -1.

 H2O +1

C12H24O11 +1

H2 0

NaH

Rules for Oxidation Numbers Oxidation # 4. The oxidation number for H

in a compound is +1 or inmetal hydrides -1.

 H2O +1

C12H24O11 +1

H2 0

NaH -1

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

SO42-

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s

SO42-

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

SO42-

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

SO42-

Total charge

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

SO42-

Total charge -8

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

SO42-

Total charge -8 = -2

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

SO42-

Total charge +6 -8 = -2

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s +6 -2

SO42-

Total charge +6 -8 = -2

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s +6 -2 +6

SO42-

Total charge +6 -8 = -2

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

PO43-

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s

PO43-

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

PO43-

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

PO43-

Total charge

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

PO43-

Total charge -8

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

PO43-

Total charge -8 = -3

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

PO43-

Total charge +5 -8 = -3

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s +5 -2

PO43-

Total charge +5 -8 = -3

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s +5 -2 +5

PO43-

Total charge +5 -8 = -3

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

Cr2O72-

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s

Cr2O72-

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

Cr2O72-

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

Cr2O72-

Total charge

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

Cr2O72-

Total charge -14

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

Cr2O72-

Total charge -14 = -2

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

Cr2O72-

Total charge +12 -14 = -2

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s -2

Divide by 2 Cr2O72-

Total charge +12 -14 = -2

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s +6 -2

Cr2O72-

Total charge +12 -14 = -2

Rules for Oxidation Numbers 5. All other oxidation numbers are assigned so that the

sum of all of the oxidation numbers is equal to the charge on the chemical species.

Oxidation #

oxidation #s +6 -2 +6

Cr2O72-

Total charge +12 -14 = -2

Oxidation #

Ca(NO3)2

Oxidation #

+2

Ca(NO3)2

Oxidation #

+2

Ca(NO3)2 +2

Oxidation #

Na2C2O4

Oxidation #

+1 -2

Na2C2O4 +2 -8 = 0

Oxidation #

+1 -2

Na2C2O4 +2 +6 -8 = 0

Oxidation #

+1 +3 -2

Na2C2O4 +3+2 +6 -8 = 0

Oxidation #

CH3COOH

Oxidation #Rewrite

C2H4O2

Oxidation #Rewrite +1 -2 0

C2H4O2 +4 -4 = 0

Oxidation #

Zn(OH)42-

Oxidation #

+2 -2 +1 +2

Zn(OH)42-

+2 -8 +4 = -2

Oxidation #

H2PtCl6

Oxidation #

+1 +4 -1 +4

H2PtCl6 +2 +4 -6 = 0

Oxidation #

Al(NO3)3

Oxidation #

+3 +5 -2 +5

Al(NO3)3 +3 +15 -18 = 0

Oxidation #

H3PO3

Oxidation #

+1 +3 -2 +3

H3PO3 +3 +3 -6 = 0

Oxidation #

Na2O2

Oxidation #

+1 -2

Na2O2 +2 -4 = 0

Exception - does not work, O must be -1

Oxidation #

+1 -1 -1

Na2O2 +2 -2 = 0

Exception - does not work, O must be -1

Oxidation #

CaH2

Oxidation #

+2 +1

CaH2 +2 +2 = 0

Exception - does not work, H must be -1

Oxidation #

+2 -1 -1

CaH2 +2 -2 = 0

Exception - does not work, H must be -1

Oxidation #

Fe(H2O)5(OH)2+

Oxidation #

0 -1

Fe(H2O)5(OH)2+

Water has a charge of 0

OH has a charge of -1

Oxidation #

0 -1

Fe(H2O)5(OH)2+

? + 0 -1 = +2

Oxidation #

0 -1 +3

Fe(H2O)5(OH)2+

? + 0 -1 = +2

Oxidation Numbers

HV2O4- V6+

 Is the above equation oxidation or reduction?

Oxidation Numbers

+3  +6HV2O4

- V6+

 Is the above equation oxidation or reduction?

Oxidation Numbers

Increase

+3  +6HV2O4

- V6+

 Is the above equation oxidation or reduction?

If the oxidation number increases it is oxidation.