Chlorine, determination solutions

Iodine monochloride [7790-99-0] ICl, mol wt 162.38, 78.16% I, is a black crystalline soHd or a reddish brown Hquid. SoHd ICl exists ia two crystalline modifications the a-form, as stable mby-red needles, d = 3.86 g/mL and mp 27.3°C and as metastable brownish red platelets, d = 3.66 g/mL, mp 13.9°C and bp 100°C (dec). Iodine monochloride is used as a halogenation catalyst and as an analytical reagent (Wij s solution) to determine iodine values of fats and oils (see Fats and fatty oils). ICl is prepared by direct reaction of iodine and Hquid chlorine. Aqueous solutions ate obtained by treating a suspension of iodine ia moderately strong hydrochloric acid with chlorine gas or iodic acid (118,119). 

In one procedure that has been widely used, the sample, after suitable treatment, is refluxed with sodium and isopropyl alcohol, after which the solution is diluted with water and the inorganic chloride is determined by standard methods (13, 54) The method has been adopted by the Association of Official Agricultural Chemists 29, 30) as a tentative one for technical DDT and for dusts, oil solutions, and aqueous emulsions of DDT, for use in the absence of other chlorine-containing compounds. The National Association of Insecticide and Disinfectant Manufacturers has also accepted the total-chlorine method for the analysis of these preparations 28). Essentially the same procedures have been described by Donovan 22), of the Insecticide Division of the Production and Marketing Administration, for technical DDT and various commercial DDT products containing no other compounds interfering with the chlorine determination. 

The metabolic fate of chlordan was studied in rabbits by analysis of the relative chlorine content of chlordan added to normal rabbit s urine and of the chlorine content of the urinary excretory product. The method of analysis was similar to the one previously used (, 4) In addition, hydrolysis of chlordan and of the urinary excretory products was carried out by adding solid sodium hydroxide to saturation to a 10-ml. solution of these substances in hot absolute ethyl alcohol. The mixture was refluxed for 3 hours in a round-bottomed flask immersed in boiling water and the amount of inorganic chlorine determined. Hydrolysis was similarly carried out with solutions of the respective substances in aqueous sodium hydroxide. 

Portions of the treated hay were extracted with benzene, and aliquots of the benzene solution were evaporated to dryness on the steam bath, with a gentle air current to remove the last traces of solvent. The residues were then taken up in deodorized kerosene and tested against houseflies by the turntable method. For comparison, extracts were made up to contain the same amounts of technical toxaphene as were indicated by the chlorine determinations to be present in the treated hay. 

In the sodium borate solution containing bromide, when the pH 4 buffer is added before the potassium iodate solution, titrations give low total residual chlorine concentrations. This loss increases with the amount of stirring time between the addition of the reagents. Even for a stirring time of 10 seconds, there is a loss of about 17% of the total residual chlorine. If the solution were stirred for 30 min, 85% of the chlorine would have disappeared. The concentration of total residual chlorine determined by the reference methods does not change throughout the experiment. This implies that this loss of chlorine does not occur in the reaction vessel, but in the titration cell as a result of the analytical procedure. 

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. 

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... 

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. 

The />H should be checked, also the available chlorine determined by titration, and adjustments to both made if necessary. The sample is moistened in distilled water, squeezed, and immersed in 100 times its w-eight of the chlorine solution at room temperature for 4 hours. It is then rinsed thoroughly, dried at room temperature, and any change of colour is assessed with the grey scale. 

The addition of halogens is also used to quantitatively determine the degree of unsaturation in vegetable oils, margarines, and shortenings (Section 8.4). Chlorine reacts with alkenes to give dichloro products in an addition reaction similar to that of bromine. However, it is not used as a test for unsaturation because it is difficult to see the pale green color of chlorine in solution. 

Pantaler et al. [4] proposed a reactive indicator paper for semiquantitative active chlorine determination in potable water. The indicator paper was made by consecutive treatment of ordinary filter paper with EDTA and Michler s thioketone solutions. To determine active chlorine, a drop of water sample was added onto a strip of indicator paper and the color produced after a few seconds was compared with a color scale. With the stripes, active chlorine in the range of 0.1—3 mg/dm in drinking water samples could be estimated. 

Fractions 1 and 2 contained cineol, which was identified from the 400616 compound it gave with resorcinol. From fractions 4 and 5 a portion boiUng between 117 and 120 (5 mm.) was separated by repeated fractionation. Saturated with hydrochloric acid gas in di-y ethereal solution at - 18, this fraction yielded a hydrc en chloride ompound which, when recrystallised from methyl alcohol, had melting-pdnt 79 to 80. The hydrochloride was inactive, the chlorine-determination gave the following result —... 

To determine which halogen is present, take 1-2 ml. of the filtrate from the sodium fusion, and add dilute sulphuric acid until just acid to litmus. Add about 1 ml. of benzene and then about 1 ml. of chlorine water and shake. A yellowish-brown colour in the benzene indicates bromine, and a violet colour iodine. If neither colour appears, the halogen is chlorine. The result may be confirmed by testing the solubility of the silver halide (free from cyanide) in dilute ammonia solution silver chloride is readily soluble, whereas the bromide dissolves with difficulty, and the iodide not at all. 

The actual form of an available chlorine bleach in solution must be determined from equations 1—4. The equiUbrium constants for equations 2 and 3 are 3.94 x 10 (9) and 2.88 x 10 M (10) at 25°C, respectively. Thus, above pH 9.5 more than 99% of the available chlorine is present as... 

Hypochlorous acid and chlorine monoxide coexist in the vapor phase (78—81). Vapor pressure measurements of aqueous HOCl solutions show that HOCl is the main chlorine species in the vapor phase over <1% solutions (82), whereas at higher concentrations, CI2O becomes dominant (83). The equihbtium constant at 25°C for the gas-phase reaction, determined by ir and uv spectrophotometry and mass spectrometry, is ca 0.08 (9,66,67,69). The forward reaction is much slower than the reverse reaction. 

Chlorine dioxide gas is a strong oxidizer. The standard reversible potential is determined by the specific reaction chemistry. The standard potential for gaseous CIO2 in aqueous solution reactions where a chloride ion is the product is —1.511 V, but the potential can vary as a function of pH and concentration (26) ... 

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