Volumetric studies in oxidation-reduction reactions : Oxidation with sodium hypochlorite iodine monochloride method

Alkaline sodium hypochlorite was used as an oxidant to determine arsenious oxide, hydrazine sulphate, ferrous ammonium sulphate, stannous chloride, sodium sulphite, potassium iodide, mercurous chloride, thallous chloride and tartar emetic, by a volumetric method, using iodine monochloride as catalyst and preoxidizer. During these titrations, the normality of the solution with respect to hydrochloric acid was kept between 5N and 7N, Chloroform was used as an indicator. Its pink colour due to the liberation of iodine during the titration turns very pale yellow at the end-point because of the formation of iodine monochloride     

Studies in oxidation-reduction reactions: Oxidation with chloramine-b indirect determinations

Chloramine-B has been used as an oxidizing agent in hydrochloric acid medium for the indirect volumetric estimations of hydrogen peroxide, lead dioxide, manganese dioxide, selenium dioxide, sodium formate, sodium sulphide, sodium metavanadate, potassium iodate and copper sulphate using iodine monochloride as a catalyst and pre-oxidiser. Chloroform is used as an indicator. It is coloured pink owing to the liberation of iodine during the titration and becomes light pale yellow at the end-point because of the formation of iodine monochloride.     

Sodium hypochlorite as volumetric reagent

Summary In presence of 5 N to 6 N hydrochloric acid, ferrous ethylenediamine sulphate was used as a reducing agent to determine indirectly potassium chlorate, potassium bromate, potassium metaperiodate, potassium dichromate, potassium ferricyanide, potassium permanganate, potassium persulphate, hydrogen peroxide, ceric sulphate and chloramine-T. An excess of ferrous ethylenediamine sulphate added to each of the substances in the acid medium was titrated with a standard solution of sodium hypochlorite. Iodine monochloride was used as catalyst and preoxidizer and chloroform was used as an indicator. Chloroform was coloured violet owing to the liberation of iodine during the titration and became very pale yellow at the end-point because of the formation of iodine monochloride.Part I: See Z. analyt. Chem. 160, 429 (1958).     

Studies in oxidation-reduction reactions: Oxidation with chloramine-b,iodine monochloride method

Chloramine-B has been used as an oxidizing agent in hydrochloric acid medium for the volumetric estimations of potassium iodide, arsenious oxide, tartar-emetic, mercurous chloride, stannous chloride, potassium thiocyanate, ferrous ammonium sulphate, hydrazine sulphate and hydroquinone, using iodine monochloride as a catalyst and pre-oxidizer. Chloroform is used as an indicator. It is coloured pink owing to the liberation of iodine during the titration and becomes light pale yellow at the end-point because of the formation of iodine monochloride.     

Volumetric studies in oxidation-reduction reactions: Oxidation with chloramine-t. iodine monochloride method

Chloramine-T has been used as an oxidizing agent in hydrochloric acid medium' for the volumetric estimations of potassium iodide, hydrazine sulphate, arscnious oxide, stannous chloride, mercurous chloride, tartar-emetic, potassium thiocyanate and ferrous ammonium sulphate, using iodine monochloride as a catalyst and pre-oxidizer. Chloroform is used as an indicator. It is coloured pink owing to the liberation of iodine during the titration and becomes very pale yellow at the end-point because of the formation of iodine monochloride.     

Sodium meta-vanadate as volumetric reagent : Iodine monochloride method (Indirect determinatios)

Sodium meta-vanadate has been used as an oxidizing agent in hydrochloric acid medium for the indirect volumetric determination of hydrogen peroxide, lead dioxide, manganese dioxide, selenium dioxide, potassium persulphate, copper sulphate, sodium formate and sodium sulphide using iodine monochloride as a catalyst, pre-oxidizer and an indicator. Chloroform is coloured pink owing to the liberation of iodine during the titration and becomes light pale yellow at the end-point owing to the formation of iodine monochloride.     

Oxidimetric methods for the volumetric estimation of sulphite

1. The use of permanganate, ceric sulphate, and dichromate for the estimation of sulphite has been reinvestigated, although these reagents have heen discarded as useless by earlier investigators. By using catalysts under controlled acid concentration, we have been able to develop conditions for the quantitative oxidation of sulphite to sulphate at room temperature by any one of these oxidizing agents, avoiding the formation of dithionate. Copper sulphate and iodine monochlonde have been found useful as catalysts with potassium permanganate and dichromate; but only iodine monochloride with ceric sulphate. 2. Sodium sulphite is also oxidized quantitatively to sulphate at room temperature, when added to excess of sodium vanadate solution containing 5 to 6N hydrochloric acid and iodine monochloride as catalyst.     

Iodine monochloride as volumetric reagent

Summary Iodine monochloride is used as volumetric reagent for the determination of arsenious oxide, tartar-emetic, hydrazine sulphate, hydroquinone, sodium sulphite, stannous chloride and potassium ferrocyanide at pH 6.5 to 7.5 in sodium acetate buffered solutions. Chloroform is employed as indicator. It becomes faintly violet at the end-point due to the liberation of iodine. In case of hydroquinone the chloroform layer changes its colour from yellow to orange at the end-point.Part I: See Z. analyt. Chem. 162, 357 (1958).     

Volumetric studies in oxidation-reduction reactions: Oxidation with chloramine-t. indirect determinations

Chloramine-T has been used as an oxidizing agent in hydrochloric acid medium for the indirect volumetric determination of hydrogen peroxide, lead dioxide, selenium dioxide, sodium formate, potassium meta-periodate, potassium permanganate and potassium dichromate using iodine monochloride as a catalyst, prcoxidizer and an indicator. Chloroform is coloured pink owing to the liberation of iodine during the titration and becomes very pale yellow at the end-point because of the formation of iodine monochloride.     

Diethylenetetra-ammonium sulphatocerate as volumetric reagent: Iodine monochloride method. Indirect determinations

In presence of 4N to N hydrochloric acid, diethylenetetra-ammnonium sulphatocerate was used as a volumetric reagent to determine indirectly potassium iodate, potassium metaperiodate, potassium dichromate, potassium bromate, ceric sulphate, hydrogen peroxide, lead dioxide and chloramine-B by the iodine monochloride method. An excess of potassium iodide added to each of the substances in the acid medium was, titrated back with a standard solution of diethylene-tetra-ammonium suphatocerate. Chloroform was used as an indicator. It was coloured violet owing to the liberation of iodine during the titralion and became very pale yellow at the end-point because of the formation of iodine monochloride.     

Diethylenetetra-ammonium sulphatocerate as volumetric reagent: Iodine monochloride method

The method of preparation of diethylenetetra-ammoniuin sulphatocerate is described. This substance has been used as an oxidant to determine potassium iodide, ferrous ammonium sulphate, arsenious oxide, stannous chloride, hydrazinc sulphate, thallous chloride. hydroquinone and potassium ferrocyanide by a volumetric method, using iodine inonochloride as catalyst and preoxidizer. During these titrations, normality of the solution with respect to hydrochloric acid has been kept at about 6N. Chloroform is used as an indicator. It is 'coloured pink owing to the liberation of iodine during the titration and becomes very pale yellow at the end-point because of the formation of iodine monochloride.     

Potassium meta-periodate as volumetric reagent : Iodine bromide method

Potassium meta-periodate has been used as an oxidising agent in acid medium for the volumetric estimationss of potassium iodide, arsenious oxide, antimonous oxide, stannous chloride, mercurous chloride, sodium sulphite, sodium thiosulphate, sodium tetrathionate, ferrous sulphate, potassium thiocyanate, hydrazine sulphate, phenylhydrazine hydrochloride and hydroquinone by the iodine bromide method. Carbon tetrachloride is used as an indicator. It is coloured pink during the titration. and becomes colourless at the end-point due to the formation of stable iodine bromide complex IBr2-, which does not dissociate, in the presence of a large excess of bromide ion.     

Potassium persulphate as volumetric reagent

Summary Potassium persulphate has been used as volumetric reagent for the direct determination of hydrazine sulphate, phenyl hydrazine hydrochloride, semicarbazide hydrochloride, thiosemicarbazide, acetone semicarbazone, benzal semicarbazone, benzalazine, aminoguanidine hydrochloride, 4-phenyl semicarbazide hydrochloride, ethylmethyl ketone semicarbazone and 4-hydroxy-3-methoxy benzal semicarbazone in hydrochlorid acid medium at room temperature, using iodine monochloride as a catalyst and preoxidiser. Chloroform was used as an indicator. It was coloured violet owing to the liberation of iodine during the titration and became very pale yellow at the end-point due to the formation of iodine monochloride. Normality of the solution with respect to hydrochloric acid was kept between 6.0 and 7.5 N in these redox titrations.     

Sodium hypochlorite as volumetric reagent

Summary Sodium hypochlorite solution has been used as an oxidising agent for the volumetric determination of semicarbazide hydrochloride, phenylhydrazine hydrochloride, benzalazine, benzalsemicarbazone, o-chlorobenzalsemicarbazone, acetonesemicarbazone, aminoguanidine hydrochloride, thiosemicarbazide, o-hydroxy benzalsemicarbazone, 3,4-methylenedioxy benzalsemicarbazone and p-methoxy benzalsemicarbazone, using iodine monochloride as catalyst and preoxidizer. During these titrations normality of the solution with respect to hydrochloric acid has been kept between 2.0 N and 3.5 N. Chloroform is used as an indicator. It is coloured pink due to the liberation of iodine during the titration and becomes very pale yellow at the end-point owing to the formation of iodine monochloride. Each hydrazino group in these compounds is oxidised quantitatively with a four-electron change to nitrogen with sodium hypochlorite as an oxidant in hydrochloric acid solution.     

Sodium metavanadate as volumetric reagent : Determination of organic derivatives of hydrazine,iodine monochloride method

Sodium metavanadate has been used as an oxidising agent in hydrochloric acid medium for the volumetric determination of semicarbazide hydrochloride, benzalazine, benzalsemicarbazone, aminoguanidine hydrochloride, o-hydroxybenzalsemicarbazone, p-methoxybenzalsemicarbazone, chloralhydrazine, o-chlorobenzalsemicarbazone and ethyl methyl ketone semicarbazone, using 10-dine monochloride as a catalyst and preoxidiser Chloroform was used as an indicator. It was coloured violet due to the liberation of iodine during the titration and became light pale yellow at the end-point owing to the formation of iodine monochloride Eachhydrazino group in these compounds was oxidised quantitatively with a four-electron change to nitrogen with sodium metavanadate as an oxidant in hydrochloric acid solution.     

Sodium meta-vanadate as volumetric reagent: Iodine monochloride method

In hydrochloric acid medium sodium meta-vanadate was used as a volumetric reagent for the determination of copper, zinc, cobalt, mercury, and lead. Cu⁺², Zn⁺² and Co⁺²were precipitated as complex mercurythiocyanates, Hg⁺² as mercuric zinc thiocyanate and Pb⁺² as Iodide. The thiocyanates were dissolved in concentrated hydrochloric acid and titrated against standard sodium meta-vanadate solution in the presence of iodine monochloride as a pie.oxidizer and catalyst. In titration of the iodide against the meta-vanadate. it was not necessary to add iodine monochloride to the titrant because it is formed during the titration. Chloroform was used as an indicator. It was pink owing to the liberation of iodine during the titration and became pale yellow at the end-point because of the formation of iodine monochlonde.     

Titration of oxalic acid with cerium sulphate at room temperature using ferroïn as internal indicator

Evidence is presented to show that, contrary to the statements of earlier workers, the reaction between ceric sulphate and oxalic acid is quite rapid in hydrochloric acid medium specially in the presence of iodine monochloride as catalyst. We have now found that the need for a temperature of 50° in the cerimetric titration of oxalic acid using ferroïn as indicator is not due to the sluggishness of the reaction between oxalic acid and Ce^IV (as believed by Willard and Young) but because of the slow reaction between oxidised ferroïn and oxalic acid in the presence of sulphate ion derived from eerie sulphate. Conditions have now been developed for the titration of oxalic acid with eerie sulphate at room temperature in lN hydrochloric acid medium using ferroïn as indicator, and barium ion as scavenger for sulphate ion, which latter markedly retards the reaction between oxalic acid and oxidised ferroïn, as well as that between oxalic acid and Ce^IV. The method now developed has several advantages over that prescribed by Willard and Young because it avoids the high temperature of 50°, where the ferroïn indicator is found to undergo some dissociation. It also avoids the use of the iodine monochloride catalyst.     

Vanadametry Estimation of Thiosulphate

1.(a) We have found that sodium thiosulphate is quantitatively oxidized to tetrathionate in five minutes at room temperature (28°) by excess sodium vanadate in a medium containing sulphuric acid at 0.06N to 0.1N concentration and a little copper sulphate as catalyst. (b) Quantitative emulation of sodium thiosulphate to tetrathionate has also been achieved by the action of excess sodium vanadate during five minutes at room temperature in a medium containing 2.0N—8.0N acetic acid and a little copper salt as catalyst. Further oxidation to sulphate does not occur, even if the mixture is heated to boiling. (c) The excess of unreacted vanadate in 1(a) and 1(b) can be titrated with a standard solution of ferrous ammonium sulphate using diphenylbenzidine as indicator, after adding the requisite quantity of syrupy phosphoric acid. 2. On the other hand, sodium thiosulphate is easily and quantitatively oxidized to sulphate at room temperature, when. acted upon by excess sodium vanadate in a medium containing hydrochloric acid at an overall concentration of 5-6N and 1.0 ml of iodine monochloride as catalyst. The time required for reaction is ten minutes. The unreacted vanadate can be estimated by titration with a standard solution of ferrous ammonium sulphate, using N-phenylanthranilic acid as indicator or with diphenylbenzidine as indicator after suitably diluting and adding phosphoric acid.     

Simple spectrophotometric and titrimetric methods for the determination of sulfur dioxide.

The proposed work describes a simple spectrophotmetric as well as a titrimetric method to determine sulfur dioxide. The spectrophotometric method is based on a redox reaction between sulfur dioxide and iodine monochloride obtained from iodine with chloramine-T in acetic acid. The reagent iodine monochloride oxidizes sulfur dioxide to sulfate, thereby reducing itself to iodine. Thus liberated iodine will also oxidize sulfur dioxide and reduce itself to iodide. The obtained iodide is expected to combine with iodine to form a brown-colored homoatomictriiodide anion (460 nm), which forms an ion-pair with the sulfonamide cation, providing exceptional color stability to the system under an acidic condition, and is quantitatively relatd to sulfur dioxide. The system obeys Beer's law in the range 5 - 100 microg of sulfur dioxide in a final volume of 10 ml. The molar absorptivity is 5.03 x 10(3) l mol(-1)cm(-1), with a relative standard deviation of 3.2% for 50 microg of sulfur dioxide (n = 10). In the titrimetric method, the reagent iodine monochloride was reduced with potassium iodide (10%) to iodine, which oxidized sulfur dioxide to sulfate, and excess iodine was determined with a thiosulfate solution. The volume difference of thiosulfate with the reagent and with the sulfur dioxide determined the sulfur dioxide. Reproducible and accurate results were obtained in the range of 0.1 - 1.5 mg of sulfur dioxide with a relative standard deviation of 1.2% for 0.8 mg of sulfur dioxide (n = 10).     

Perbenzoic acid as volumetric reagent

Summary Perbenzoic acid (0.05 M) chloroform solution is used as volumetric reagent for the determination of potassium ferrocyanide, arsenious oxide, tartar emetic, sodium sulphite, stannous chloride, hydrazine sulphate and sodium thiosulphate atph 4.0 to 4.5 in sodium acetate and acetic acid buffer solutions, using iodine as catalyst and preoxidiser. Appearance of faint violet colour in chloroform layer indicates the end point in visual titrations. In potentiometric titrations bright platinum foil is used as an oxidation-reduction electrode and it is coupled with saturated calomel electrode. At the equivalence point there is a sharp jump in potential in each titration.