L1 /
5
CH1012
OXIDATION STATE
METHOD
The variation in the oxidation state of the carbons may also be used to work out if the organic half-rxn is an oxidation or reduction.
The
following rules are used for C-bonding.
1) if a bond is to H (or an atom < EN than C)
then -1 is added to C
1) if a bond is to H (or an atom < EN than C)
then -1 is added to C
2) if a bond is
to O, N, halogen (or an atom >
EN than C) then +1 is added to C
EN than C) then +1 is added to C
3) if a bond is to another C then add 0 to C
eg. CH4 C -IV CH3CH3 C -III CO2 C +IV
CH3CH=CH2 ® CH3CH(OH)C(OH)H2
-III -I -II -III 0 -I
Sum: -VI -IV + 2e-
-III -I -II -III 0 -I
Sum: -VI -IV + 2e-
