Cerium titrimetric

Cerium(IV) solutions in 0.1 M solution are not too highly coloured to obstruct vision when reading the meniscus in burettes and other titrimetric apparatus. 

Determination of cerium as cerium(IV) iodate and subsequent ignition to cerium(IV) oxide Discussion. Cerium may be determined as cerium(IV) iodate, Ce(I03)4, which is ignited to and weighed as the oxide, Ce02. Thorium (also titanium and zirconium) must, however, be first removed (see Section 11.44) the method is then applicable in the presence of relatively large quantities of lanthanides. Titrimetric methods (see Section 10.104 to Section 10.109) are generally preferred. 

Titrimetric methods also measure gold in solution. Gold(llI) may be reduced by excess hydroquinone which may be back titrated with a standard solution of cerium(lV) titrant. (4old(lll) may also be determined by iodometric titration. 

Measurement of Reaction Rates by Titrimetry. The rates of cerium(IV) consumption by each of Cr(C204)3 3, m-Cr(OH2)2(C204)2 and Cr(0H2)4C204+ were also measured by a direct titrimetric method. Solutions were prepared and mixed as for the spectrophotometric procedure. At appropriate times aliquots of the reactant solutions were quenched with known volumes of standard ferrous sulfate, and the excess ferrous ion was titrated potentiometrically with standard potassium dichromate,... 

The possible influence of oxygen was checked by using the titrimetric method to study the consumption of cerium(IV) by m-Cr(OH2)2(0204)2 in the absence of oxygen. Component solutions were introduced into a closed container, flushed with nitrogen, and without exposure to the atmosphere, mixed, and allowed to react. The usual method for quenching was used. Comparison of the results for a series of solutions studied in this way with the results for similar solutions studied by the ordinary procedure indicated that the exclusion of oxygen has no measurable effect on the rate of the reaction. 

Several reports describe the mechanism of polymerisations using cerium compounds in combination with alcohols77,78, diols79,80 and polyols81. Only in a limited number of kinetic studies was the concentration of cerium ions measured during the polymerisation reaction. Mohanty et alm, Rout et al.m, Jayakrishnan et al.65 and Gupta and Behani.67 followed the reduction of Ce(IV) ions titrimetrically. 

Quadrivalent cerium was first used as a titrimetric oxidizing agent in 1927 by Martin. Systematic studies of its uses were begun soon thereafter by Furman and Willard. The rate and extent of reaction with reductants is affected by the solvent, by pH, and by complex formation, and mechanisms of reactions often have been difScult to untangle. 

The anhydrous salt [Co(NH3)g][Co(C03)3] made by the method of McCutcheon and Schule or more simply by adding [Co(NHj)gPC3 to a green solution prepared by Procedure 1, is much more stable when it is dry. The compound is soluble to the extent of only ca. 0.04 g per 100 cm of water at room temperature, the solution being quite unstable. However, the compound is ten times more soluble in an aqueous solution of potassium or sodium bicarbonate. Baur and Bricker used this compound as a reagent for titrimetric oxidation the compound is a very weak oxidant in bicarbonate media, but in an acid solution the cobalt(III) in the [Co(C03)3] portion is released and reacts quantitatively with reductants such as iron(II), vanadium(IV) and cerium(III). 

ISO (2005d) Determination of plutonium by controlled potential coulometry, ISO-12183. ISO, Geneva ISO (2007a) Determination of uranium in solutions, uranium hexafluoride and solids, iron(II) reduc-tion/cerium(IV) oxidation titrimetric method, ISO 7097-2,1st edn. ISO, Geneva ISO (2007b) Tank calibration and volume determination for nuclear material accountancy, IS018213-1 to 6. ISO, Geneva... 

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