Chlorine, determination acid solutions

E5.14 Consult Section 5.12(b) of your textbook for a detailed explanation. The Latimer diagram for chlorine in acidic solution is given in Resource Section 3. To determine the potential for any non-adjacent couple, you must calculate the weighted average of the potentials of intervening couples. In general terms it is ... 

Second-order rate coefficients have been obtained for chlorination of alkyl-benzenes in acetic acid solutions (containing up to 27.6 M of water) at temperatures between 0 and 35 °C, and enthalpies and entropies of activation (determined over 25 °C range) are given in Table 63 for the substitution at the position indicated266. 

Use data from Appendix 2B to determine whether chlorine gas will oxidize Mn2+ to form the permanganate ion in an acidic solution. 

The compound is digested with nitric acid and the solution is analyzed for antimony by AA or ICP spectrophotometry (see Antimony). To determine the chlorine content a measured amount of substance is heated at 300°C and the liberated CI2 is passed into an acidic solution of KI and analyzed by iodomet-ric titration using a standard solution of sodium thiosulfate or phenyl arsine oxide and starch indicator. 

When a quantitative determination of the phosphoric acid and chlorine is required, a fresh quantity of ash is prepared from a weighed amount of the meat sample mixed with an alkali such as milk of lime, sodium carbonate, etc. The phosphoric acid and the chlorine are determined in the nitric acid solution of the ash, the former by the ammonium molybdate method, and the latter either volumetrically or gravimetrically as silver chloride. 

Determination of the Chlorides.—50 c.c. of the wine, rendered faintly alkaline with caustic soda solution,1 are evaporated to dryness in a platinum dish and the residue carefully incinerated as described on p. 190. The ash is extracted with hot water acidified with nitric acid and the chlorine determined in the solution obtained, which should be distinctly acid ... 

Chlorine.—1 gram of the substance is fused with nitre and sodium carbonate, the mass being dissolved in water, the solution acidified with nitric acid, and the chlorine determined either gravimetrically as silver chloride or volumetrically by Volhard s method. 

Chlorine.—In a platinum dish 3-5 grams of the leather are evaporated to dryness with 25 c.c. of pure 10% sodium carbonate solution, the residue being incinerated and taken up in water the solution is neutralised with nitric acid and the chlorine determined by the ordinary gravimetric or volumetric method. 

If the fibres are strongly coloured or dressed, they are cleaned as far as possible by boiling with dilute sodium carbonate solution (o-i%) and then with 3-5% hydrochloric acid in the manner indicated on p. 458 for determining the dressing in cotton fabrics. If the coloration is not sufficiently diminished in this way, the fibres may be treated with chlorine water (not too concentrated) or with dilute chromic or oxalic acid solution. They are then washed well in running water. 

Adjust the pH of the sample to between 11.5 and 12. To 20 mL of sample in a 50 mL volumetric flask, add 5 mL of phosphate buffer and 2 drops of EDTA solution. Add 2 mL chloramine-T solution and stir well. Test for residual chlorine using Kl-starch paper. If required, add more chloamine-T so that there is enough residual chlorine in the solution. Allow the solution to stand for exactly 3 min. After this, add 5 mL pyridine-barbituric acid and mix well. Dilute to 50 mL mark. Let the solution stand for 8 min. Measure the absorbance at 578 nm in a 1 cm cell against distilled water. Determine the GNL concentration from the calibration curve. 

Chlorine, determination of, in chlorine(I) oxide in carbon tetrachloride and hypochlorous acid solutions, 5 162, 164 Chlorine(I) compounds, 5 156 Chlorine(I) oxide, 5 156 in carbon tetrachloride solution, 5 158, 159 analysis of, 5 162 Chlorine(IV) oxide, 4 152 admixed with inert gas and chlorine, 4 153... 

It is of esjx cial importance to know the potential interval within which one or several distinct reactions take place. The determination of this depends upon the change in potential which the presence of a depolarizer produces as opposed to an electrolyte containing no depolarizer. For example, if it is desired to learn if chlorine derivatives of phenol can be prepared at the anode by electrolysis of a hydrochloric-acid solution of phenol, then the point of decomposition of the chlorine ion, in combination with the hydrogen electrode, is found at LSI volts in a l/i n-hydrochloric-acid solution. If phenol is added to this solution, the break in the curve occurs already at 0.1) volt.2 Therefore the span in potential, within which the reaction for the formation of chlorine derivatives of phenol must take place, lies between 0.9 and 1.3 volts. In thin manner Dony-H6nault, among others, determined the decomposition potential of the OH ions, in combination with the hydrogen electrode, in dilute sulphuric-acid solution both without and with the addition of ethyl alcohol. He found... 

The absorption spectrum of Po in HCl solutions reveals the presence of at least two complexes, A and B. Complex A absorbs with a maximum at 344m a. Complex B absorbs with a maximum at 418 m j,. The 418m a absorption can be used for the colorimetric determination of polonium. Although the 344m j, absorption is stronger in weakly acidic solutions, it is difficult to utilize because of chlorine formation brought about by radiation from the polonium. The absorbance of the complex at 344 m a was estimated by the use of a method involving the log absorbancy curves for the complex and for the chloride ion. 

Bleachex manufactures a variety of products using concentrated acids and bases. Plant officials noticed a large quantity of liquid, which was believed to be either sodium hydroxide or hydrochloric acid solution, flowing through the loading bay doors. An Emergency Toxic Spill Response Team attempted to determine the source and identity of the unknown liquid. A series of explosions and the presence of chlorine gas forced the team to abandon its efforts. The unknown liquid continues to flow into the nearly full containment ponds. 

For the determination of chlorine, the mixture is first heated to 115 at 30 mm. pressure. This removes any water and dichlorhydrin. About 5 g. is weighed out and boiled for fifteen minutes with 10 c.c. of a 15 per cent, solution of sodium hydroxide in alcohol. The alcohol is evaporated off and a little water is added. This is boiled for a few minutes and the liquid is acidified with nitric acid and the chlorine determined. The value is somewhat too high owing to the presence of small quantities of dichlorhydrin. 

A cell is constructed at 25°C as follows. One half-cell consists of a chlorine/chloride, CI2/CE, electrode with the partial pressure of CI2 = 0.100 atm and [Cl ] = 0.100 M. The other halfcell involves the Mn04 /Mn + couple in acidic solution with [Mn04 ] = 0.100 M, [Mn +] = 0.100 M, and [H ] = 0.100 M. Apply the Nernst equation to the overall cell reaction to determine the cell potential for this cell. 

Chloride is oxidized with potassium periodate in a dilute sulphurie acid solution. The solution of KIO4 in H2SO4 is first heated to distil off any chlorine formed from ehloride impurities in the reagents. The optimum acid concentration for the Methyl Red colour reaction with chlorine is 1 M H2SO4. Bromide and iodide interfere in this method. The presence of 5 pg of Br" increases the results by 60-70% in the determination of 5 pg of Cl. Positive errors owing to iodide are smaller and less reproducible, than those owing to bromide. 

For the analysis of rhenium, the sample is fused with sodium peroxide and rhenium precipitated from hydrochloric acid solution as Re2S7 by hydrogen sulfide. The precipitate is dissolved in aqueous sodium peroxide and from dilute sulfuric acid solution, rhenium is determined by electrodeposition.8 Chlorine is determined gravimetrically by fusion of the sample with a sodium carbonate/ sodium nitrate mixture (95 5) in a platinum crucible and then precipitating as silver chloride. 

Procedure. The procedure outlined above is followed except that the indicated volume of hypochlorous acid solution is added in place of the carbon tetrachloride solution. The same end points are determined, but correction is made for hydrogen ion supplied by the chloric acid present to eliminate reported hypochlorous acid contents which are too low and chlorine contents which are too high. It is assumed that no iodine is liberated by chloric acid. 

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