Acidimetry

Acidimetry - the aggregate volume (titrimetric) analysis methods, which are based on oxidation-reduction reactions. Acidimetry is subdivided into iodometry, brummeria, permanganatea etc. All of these methods are widely used in clinical and sanitary-hygienic laboratories.
Iodometry based on oxidation-reduction reactions:
which, depending on the nature of the analyzed substances and conditions can occur in both forward and reverse direction. In the determination of reducing agents use direct response:
In this case, the amount of the analyzed solution to which was added a few drops of the indicator solution of starch), titrated work iodine solution of known concentration until blue coloration. The change of colour indicates that the whole defined the restorer of oxidized. When determining oxidants use feedback:
In this case the analyzed solution is acidified and add to it the significant excess solution of potassium iodide. Emitted when the iodine in the amount equivalent to define the oxidant, titrated work sodium thiosulfate solution, the concentration of which are known. Before the end of titration (titrated solution stained with iodine in a weak yellow) to the solution add a few drops of the solution of starch and titration continue until the disappearance of blue color. Thiosulfate reacts with iodine by the equation: 2Na2S2O3 + I2 = 2NaI + Na2S4O6.
Normal concentration (H) analysing substances is calculated by the formula:
, where Hp - normal concentration of the working solution, V - volume of the analyzed solution, Vp - volume work solution, gone on titration.
In the basis of permanganatea lies reaction between potassium permanganate KMnO4, which is the oxidant, and any reducing agent. The reaction is carried out in an acidic environment. This heptavalent manganese restored to divalent:
In the determination of reducing agents analyzed solution was acidified with sulphuric acid, titrated working solution of potassium permanganate until weak pink color solution, indicating that the whole defined the restorer of oxidized and in solution appeared ions MnO4. The normal concentration of reducing agent is calculated by the formula (1). When determining oxidants analyzed solution is acidified with sulphuric acid and add to it measured the amount of reducing agent (usually FeS04)taken in excess compared to the defined oxidant. Unreacted excess FeS04 titrated work permanganate solution. Normal concentration determined oxidant calculated by the formula:
where V, V1 and V2 - the volume of the analyzed solution, solution FeSO4 and the working permanganate solution, gone on titration of excess FeSO4, respectively; H1, H2- normal concentration of solutions FeSO4 and KMnO4.
Cm. also the Concentration of the Titration.

Acidimetry - a set of methods bulk chemical analysis, based on oxidation-reduction reactions. As a result of these reactions of some substances (reducing agents) are oxidized, while others (oxidants) is restored; oxidizing substance loses electrons, and recovering their purchases. For example, the interaction of a trivalent ions of iron ions of iodine
2Fe3++2J-=2Fe2J++2
iodine ions lose electrons and become oxidized to free iodine: 2J--2e=J2, and ferric ions, adding electrons, recovered to a bivalent iron ions (Fe3++e=Fe2+. In each of redox reactions the number of electrons lose a reducing agent, equal to the number of electrons that are purchased oxidant. The essence of oksiginatsii is to measure by titration (see) volume of working solution of this oxidizer (reducing)that you want to spend on full oxidation (or restoration) of investigated substances contained in a given volume of solution, taken for titration. According to the titration of normality and compute or the titer T (see Concentration) researched solution:
where nis 0 and V0 - normality and the amount of working solution, V and e - solution volume and is equivalent to the weight of the analyte.
Of the many methods of oksiginatsii in sanitary-hygienic, clinical, pharmaceutical and biochemical laboratories of the most widely used permanganatea and Lodomeria. In permanganatea as a working solution using potassium permanganate solution - KMP, the concentration of which are well established and generally close to 0,05 N. Determination of reducing agents produce direct titration researched solution working solution KMPO4. The definition of oxidizing agents carried out by the method of inverse titration (see). Titration solution CMP usually produce no indicator and finish as soon as titrated solution becomes weak crimson color due to the appearance at the end of titration small surplus ions MnO4.
In iodometry apply two working solution: the solution of iodine - J2 and the solution of thiosulfate (Hypo) sodium - Na2S2O3concentrations are fixed and usually close to 0,05 N. Iodine determination of reducing agents are produced by the method of inverse titration. To do this, to the solution of the restorer poured precisely measured amount (taken in excess) of a working solution of iodine. Part of iodine, not included in the response from the designated reducing agent, titrated work sodium thiosulfate solution. Iodometric definition of oxidants produced by adding to the volume of solution oxidant excess solution of potassium iodide is KJ. The ions of iodine - J - are oxidized to free iodine - J2, which is titrated with sodium thiosulfate. Thus, iodine determination as oxidants and reducing agents is reduced to the free iodine titration work sodium thiosulfate solution. To determine the end of titration (the equivalence point) as an indicator used solution of starch, 2-3 ml of which add to titrated solution. With the free iodine-starch turns blue titration lead to the disappearance of blue color solution.