OXIDATION – REDUCTION REACTIONSChemical reaction involves an electronexchange between the reactants. onesubstances loses electrons and anothersubstance gains electrons or gains agreater share of them these reactions arecalled oxidation – reduction reactions.
OXIDATION; is the loss ofelectrons andREDUCTION; is the gain ofelecrrons
for example:A c-x bond . If when the bond is broken , theelectrons are left with c, c takes on a negative chargeand is called a carbon anion.If the electrons leave with x, then c is left with apositive charge and is a carbon cation
OXIDIZING AGENT;Substances that causes another substance to loseelectronsREDUCING AGENT;Substance that loses electrons in a chemical reaction; itreduces another substance by losing electrons to it
CHEMICAL REACTIONS: Example: REACTANTS PRODUCT 2Na + Cl2 2Na+ Cl- LOSS GAIN Oxidized ReducedReducing Agent Oxidizing Agent
Gain and Loss of Hydrogen• An alternative approach is to describe oxidation as the loss of hydrogen and reduction as the gaining of hydrogen.• 2CH4 + 2O2 -> CO2 + 2H2O With this approach it is clear that the carbon is oxidized (loses all four hydrogens) and that part of the oxygen is reduced (gains hydrogen).• Another reaction where the hydrogen approach makes things clearer is the passing of methanol over a hot copper gauze to form formaldehyde and hydrogen gas CH3OH -> CH2O + H2
Oxidation Number or Oxidation StateReflects the number of electrons lost or gained inrelation to the elemental state.For example: Na0 , Mg0 , and so on.For example: Na1+, Mg2+