OXIDATION AND REDUCTIONREDOX REACTIONSOXIDATION AND REDUCTION REACTIONS

Chemical reaction involving oxidation and reduction occurring simultaneously

Redox reactions can be explained based on :Loss or gain of oxygen,Loss or gain of hydrogen,Transfer of electron (release and gain ),Changes in oxidation number

Redox reaction based on loss or gain oxygenOxidation : gain of oxygenReduction : loss of oxygen

The substance that gains oxygen is oxidisedThe substance that loss oxygen is reducedThe substance that causes oxidation is oxidising agentThe substance that causes reduction is reducing agent

Redox reaction based on loss or gain hydrogenOxidation : loss of hydrogenReduction : gain of hydrogen

H2S + Cl2 S + 2HCl

H2S : Oxidised Reducing agentCl2 : Reduced Oxidising agent

Redox reaction based on transfer of electronOxidation : loss of electrons ( e- donor )Reduction : gain of electron ( e- acceptor ) OIL RIG

The substance that donate e- : is oxidised : reducing agentThe substance that accept e- : is reduced : oxidising agent

Redox reaction based on changes in oxidation number of an elementOxidation number of an element is thecharge that the atom of the element wouldhave if complete transfer of electrons occurs

Rules for assigning oxidation number, Calculate the oxidation number, Oxidation number and nomenclature of compound

ConclusionYou may use any one of the four definitionsto understand a redox reaction.

You should realize that not all chemical reactions are classified as redox reaction.

Examples of redox reactionChange of iron(II) ion to iron(III) ion.Change of iron(III) ion to iron(II) ion.Displacement of metal from its salt solutionDisplacement of halogen from its halide solutionTransfer of electrons at a distance

Examples of redox reactionsRustingExtraction of metal from its ore ( Reactivity series of metals )Reaction in electrolytic and chemical cells