Reductor

Jones reductor A tube containing zinc amalgam. Used for reduction of solutions (e.g. 

Two common reduction columns are used. In the Jones reductor the column is filled with amalgamated Zn prepared by briefly placing Zn granules in a solution of ITgCb to form Zn(lTg). Oxidation of the amalgamated Zn... 

The amount of Fe in a 0.4891-g sample of an ore was determined by a redox titration with K2Cr20y. The sample was dissolved in HCl and the iron brought into the +2 oxidation state using a Jones reductor. Titration to the diphenylamine sulfonic acid end point required 36.92 mL of 0.02153 M K2Cr20y. Report the iron content of the ore as %w/w FeyOy. 

Jones reductor a reduction column using a Zn amalgam as a reducing agent, (p. 341)... 

Jojoba oil Jojoba oil [61789-91-1] Jojoba wax [66625-78-3] Jominy test Jones reductor Jones separator Joosten method Jordan refiner Josamycin [16846-24-5]... 

Discussion. Copper(II) ions are quantitatively reduced in 2M hydrochloric acid solution by means of the silver reductor (Section 10.140) to the copper(I) state. The solution, after reduction, is collected in a solution of ammonium iron(III) sulphate, and the Fe2+ ion formed is titrated with standard cerium(IV) sulphate solution using ferroin or AT-phenylanthranilic acid as indicator. 

Procedure (copper in crystallised copper sulphate). Weigh out accurately about 3.1 g of copper sulphate crystals, dissolve in water, and make up to 250 mL in a graduated flask. Shake well. Pipette 50 mL of this solution into a small beaker, add an equal volume of ca AM hydrochloric acid. Pass this solution through a silver reductor at the rate of 25 mL min i, and collect the filtrate in a 500 mL conical flask charged with 20 mL 0.5M iron(III) ammonium sulphate solution (prepared by dissolving the appropriate quantity of the analytical grade iron(III) salt in 0.5M sulphuric acid). Wash the reductor column with six 25 mL portions of 2M hydrochloric acid. Add 1 drop of ferroin indicator or 0.5 mL N-phenylanthranilic acid, and titrate with 0.1 M cerium(IV) sulphate solution. The end point is sharp, and the colour imparted by the Cu2+ ions does not interfere with the detection of the equivalence point. 

A suitable form of the Jones reductor, with approximate dimensions, is shown in Fig. 10.17. A perforated porcelain plate, covered with glass wool, supports... 

REDUCTION WITH AMALGAMATED ZINC THE JONES REDUCTOR 10.138... 

Carry out a blank determination, preferably before passing the iron solution through the reductor, by running the same volumes of acid and water through the apparatus as are used in the actual determination. This should not amount to more than about 0.1 mL of 0.02M permanganate, and should be deducted from the volume of permanganate solution used in the subsequent titration. 

It must be emphasised that if hydrochloric acid has been employed in the original solution of the iron-bearing material, the volume should be reduced to ca 25 mL and then diluted to ca 150mL with 5 per cent sulphuric acid. The determination is carried out as detailed above, but 25 mL of Zimmermann-Reinhardt or preventive solution must be added before titration with standard potassium permanganate solution. For the determination of iron in hydrochloric acid solution, it is more convenient to reduce the solution in a silver reductor... 

Applications and limitations of the Jones reductor. Solutions containing 1-10 per cent by volume of sulphuric acid or 3-15 per cent by volume of concentrated hydrochloric acid can be used in the reductor. Sulphuric acid is, however, generally used, as hydrochloric acid may interfere in the subsequent titration, e.g. with potassium permanganate. 

Other ions which are reduced in the reductor to a definite lower oxidation state are those of titanium to Ti3+, chromium to Cr2+, molybdenum to Mo3+, niobium to Nb3+, and vanadium to V2 +. Uranium is reduced to a mixture of U3 + and U4+, but by bubbling a stream of air through the solution in the filter flask for a few minutes, the dirty dark-green colour changes to the bright apple-green colour characteristic of pure uranium(I V) salts. Tungsten is reduced, but not to any definite lower oxidation state. 

The silver reductor has a relatively low reduction potential (the Ag/AgCl electrode potential in 1M hydrochloric acid is 0.2245 volt), and consequently it is not able to effect many of the reductions which can be made with amalgamated zinc. The silver reductor is preferably used with hydrochloric acid solutions, and this is frequently an advantage. The various reductions which can be effected with the silver and the amalgamated zinc reductors are summarised in Table 10.11. ... 

Silver reductor hydrochloric acid solution Amalgamated zinc (Jones) reductor sulphuric acid solution... 

The dark silver chloride coating which covers the silver of the upper part of the reductor when hydrochloric acid solutions are employed moves further down... 

Although as already stated the use of metal amalgams, and in particular use of the Jones reductor or of the related silver reductor, is the best method of reducing solutions in preparation for titration with an oxidant, it may happen that for occasional use there is no Jones reductor available, and a simpler procedure will commend itself. In practical terms, the need is most likely to arise in connection with the determination of iron, for which the reduction of iron(III) to iron(II) may be necessary. 

Determination of uranium with cupferron Discussion. Cupferron does not react with uranium(VI), but uranium(IV) is quantitatively precipitated. These facts are utilised in the separation of iron, vanadium, titanium, and zirconium from uranium(VI). After precipitation of these elements in acid solution with cupferron, the uranium in the filtrate is reduced to uranium(IV) by means of a Jones reductor and then precipitated with cupferron (thus separating it from aluminium, chromium, manganese, zinc, and phosphate). Ignition of the uranium(IV) cupferron complex affords U308. 

Reductant equivalent weights of, 847 Reduction 409 by chromium(II) salts, 409 by hydrogen sulphide, 416 by Jones reductor (zinc amalgam), 410 by liquid amalgams, 412 by silver reductor, 414 by sulphurous acid, 416 by tin(II) chloride, 415 by titanium(II[), 410 by vanadium(II), 410 see also Iron(III), reduction of Reduction potentials 66 Reference electrodes potentials, (T) 554 Relative atomic masses (T) 819 Relative error 134 mean deviation, 134... 

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