EXP 23

• Oxidation is defined as a reaction in which an atom or an ion losses electrons and thereby gains positive charges
• reduction is a reaction in which an atom or an ion gains electrons.
• Reduction results in an increase in its negative charges or a decrease in its positive charges.
• the oxidizing agent (O.A.) is reduced, that is, it gains electrons
• reducing agent (R.A.) loses electrons and is, therefore, oxidized.
• standard solutions of oxidizing agents and of reducing agents take the place of the acid and akali solutions of the neutralization processes.
• Important oxidizing agents employed as standard solutions include - potassium dichromatepotassium permanganate, potassium ferricyanide, potassium iodate, potassium bromate, iodine, and ceric sulfate.
• Important reducing agents that are used in the form of standard solutions include ferrous sulfate, (or ferrous ammonium sulfate), oxalic acid, sodium oxalate, sodium thiosulfate, titanous chloride, and sodium arsenite.
• Other reducing agents, such as sulfurous acid, hydrogen sulfide, and zinc, may take part in the processes but not as standard solutions.
• Permanganate method of titration makes use of a permanganate solution as the standard solution for neutralization.
• It also serves as an indicator in titrations where it is used, since a very slight excess permanganate imparts to solutions a distinct pink color at the end point. .
• The determination of iron in such materials as iron ores, alloys, cement, etc., can be done quantitatively by titrating a solution containing iron (II) ions with a standard solution of potassium permanganate in an acidic medium.
• The reaction involved is a redox reaction in which iron (II) ion is oxidized by the permanganate ion into the iron (III) ion – oxidation state.
• the permanganate ion reduced to manganese (II) ion.
• the equivalent weight of the oxidizing agent and the reducing agent is equal to the formula weight divided by the total change invalence.