Redox-Titration

The redox titration in chemistry with a concentration determination by titration method. It can be used the determine the content of substances that oxidize or be reduced.

Basics

When Oxidimetrie allowed the substance to be determined react with an oxidizing or reducing solution ( redox reaction ). Once the substance to be determined is fully oxidized or reduced by gradual dropwise addition of the standard solution is the next drop of standard solution before any more reactants. The disappearance of the substance to be determined or the now excess in the sample solution used must be recognized as the end point of the reaction in order to determine the hitherto consumed amount of titrant can.

Frequently used methods are the bromatometry be used in the bromate as an oxidant:

The Manganometry that permanganate is used as the oxidizing agent:

And the Cerimetry, are used in the tetravalent cerium ions for the oxidation:

Meanwhile, more rarely the potassium dichromate method is used, with dichromate ions act as oxidizing agents:

Here, for example, Diphenylamine be used as a redox indicator. Similarly, with iron ( II ) sulfate can be titrated, but they does the Mohr salt ( ammonium iron (II ) sulfate ) used for the standard solution.

Another example is the iodometry is reduced in either of iodine to iodide, such as for the determination of tin ( II) salts, or iodide is oxidized to iodine, such as the determination of hydrogen peroxide.

Detection of reaction end point

Through self- indication

The self- indication is mainly in the Manganometry ( KMnO4 ) and iodometric (though by adding strength, since iodine with starch forms a colored complex ) exploited because potassium permanganate and iodine are colored solutions.

During the direct titration, the acid solution is added continuously discolored by the reaction with the sample. When the reaction is complete, ie all sample substance has reacted, the standard solution is not implemented and therefore stains the titration solution.

With the help of redox indicators

Redox indicators are substances which are themselves oxidized or reduced and therefore show a color change. eg ferroin. Not redox-active substances may act as indicators, such as displays in bromatometry discoloration due to destruction of the dye, the end point of the reaction.

Potentiometric

During a redox titration, the voltage between the sample solution and an electrode modified. In the potentiometric method you can pay this measured voltage as a function of added titrant volume, we obtain a titration curve, which can be evaluated graphically or mathematically.