Redox Question Help

[john216]

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How do you calcualte change in oxidation of oxygen in this reaction?
ex. C5H12 + 8 O2 -> 5 CO2 + 6 H2O


So on left, O2 is elemental form, it would be 0 e-.

But on right, as you see, there are oxygens present in both CO2 and H2O having oxidation # of 2e- on both.

do you just add those up to 4 e-?
so the total # of electrons are going from 0e- to 4 e-?


Thanks

 

[Cmdr_Shepard]

Each oxygen atom gains 2 electrons. 10 oxygens gain when they're forming the bonds with carbon, and 6 oxygens gain 2 each when they're forming water. A total of 32 electrons are transferred from sources to oxygen.

Oxygen is being reduced while carbon is being oxidized.

So oxygen's oxidation number is going from 0 to -2.