Chloride ion titration

Anchoring polymers are prepared from chloromethylated styrene-divinylbenzene copolymers of either 1 equiv Cl/g or 4 equiv Cl/g capacity. These resins arc stirred for 24 h in refluxing CHC13, with either 1,4-diazabicyclo[2.2.2]octane, hexamethylenetetramine, or TMEDA. The polymers are filtered off, washed with ClIClj, acetone and Et20, then dried overnight under vacuum at 25 °C. Nitrogen elemental analysis and chloride ion titration gives a value of 80-90% quaternarization. 

Figure 4. Calcium stearate transformation from chloride ions titration (Curve 1) or from stearic acid titration (Curve 2) in the sheets of rigid FVC heated in a stove at 180°C under nitrogen atmosphere...

Chloride. Chloride is common in freshwater because almost all chloride salts are very soluble in water. Its concentration is generally lO " to 10 M. Chloride can be titrated with mercuric nitrate. Diphenylcarbazone, which forms a purple complex with the excess mercuric ions at pH 2.3—2.8, is used as the indicator. The pH should be controlled to 0.1 pH unit. Bromide and iodide are the principal interferences, whereas chromate, ferric, and sulfite ions interfere at levels greater than 10 mg/L. Chloride can also be deterrnined by a colorimetric method based on the displacement of thiocyanate ion from mercuric thiocyanate by chloride ion. The Hberated SCN reacts with ferric ion to form the colored complex of ferric thiocyanate. The method is suitable for chloride concentrations from 10 to 10 M. 

Impurities in bromine may be deterrnined quantitatively (54). Weighing the residue after evaporation of a bromine sample yields the total nonvolatile matter. After removing the bromine, chloride ion may be deterrnined by titration with mercuric nitrate, and iodide ion by titration with thiosulfate water and organic compounds may be detected by infrared spectroscopy sulfur may be deterrnined turbidimetricaHy as barium sulfate and heavy metals may be deterrnined colorimetricaHy after conversion to sulfides. 

Other ions, eg, ferrate, chloride, and formate, are determined by first removing the cyanide ion at ca pH 3.5 (methyl orange end point). Iron is titrated, using thioglycolic acid, and the optical density of the resulting pink solution is measured at 538 nm. Formate is oxidized by titration with mercuric chloride. The mercurous chloride produced is determined gravimetricaHy. Chloride ion is determined by a titration with 0.1 Ai silver nitrate. The end point is determined electrometricaHy. 

IQ. To determine the concentration of chloride ion, - a 5-mL aliquot of the methyl lithium solution is cautiously added to 25 ml of water and the resulting solution is acidified with concentrated sulfuric acid and then treated with 2-3 ml of ferric ammonium sulfate [Fe(NH4)( 04)2 12 H2O] indicator solution and 2-3 ml of benzyl alcohol. The resulting mixture is treated with 10.0 mL of standard aqueous 0.100 M silver nitrate solution and then titrated with standard aqueous 0.100 H potassium thiocyanate solution to a brownish-red endpoint. 

Sodium Chloride [25]. Sodium chloride estimation is based on sodium titration. To 20 ml of a 1 1 mixture of toluene (xylene) isopropyl alcohol, add a 1-ml sample of oil-base mud, stirring constantly and 75 to 100 ml of distilled water. Add 8-10 drops of phenolphthalein indicator solution and titrate the mixture with H SO (N/10) until the red (pink) color, if any, disappears. Add 1 ml of potassium chromate to the mixture and titrate with 0.282N AgNO (silver nitrate, 1 ml = 0.001 g chloride ions) until the water portion color changes from yellow to orange. Then... 

Theory. The anion exchange resin, originally in the chloride form, is converted into the nitrate form by washing with sodium nitrate solution. A concentrated solution of the chloride and bromide mixture is introduced at the top of the column. The halide ions exchange rapidly with the nitrate ions in the resin, forming a band at the top of the column. Chloride ion is more rapidly eluted from this band than bromide ion by sodium nitrate solution, so that a separation is possible. The progress of elution of the halides is followed by titrating fractions of the effluents with standard silver nitrate solution. 

The small amount of mercury(I) chloride in suspension has no appreciable effect upon the oxidising agent used in the subsequent titration, but if a heavy precipitate forms, or a grey or black precipitate is obtained, too much tin(II) solution has been used the results are inaccurate and the reduction must be repeated. Finely divided mercury reduces permanganate or dichromate ions and also slowly reduces Fe3+ ions in the presence of chloride ion. 

The chlorine content can be determined by either chlorine elemental analysis or a potentiometric titration using a chloride-ion electrode. For titration, about 0.2 g. of polymer is heated in 3 ml. of pyridine at 100° for 2 hours. This suspension is then transferred to a 50-mi. beaker containing 30 ml. of aqueous 50% acetic acid and 5 ini. of concentrated nitric acid, and the resulting mixture is titrated against aqueous 0.1 N silver nitrate. 

The methods most commonly used to detect hydrogen sulfide in environmental samples include GC/FPD, gas chromatography with electrochemical detection (GC/ECD), iodometric methods, the methylene blue colorimetric or spectrophotometric method, the spot method using paper or tiles impregnated with lead acetate or mercuric chloride, ion chromatography with conductivity, and potentiometric titration with a sulfide ion-selective electrode. Details of commonly used analytical methods for several types of environmental samples are presented in Table 6-2. 

The intercalant solution was prepared by titration of an Al3+/ Fe3+cationic solution with 0.2 molL"1 NaOH. The cationic solution contained 0.18 and 0.02 molL"1 of A1C13 and FeCl3, respectively. The NaOH solution was slowly added to the cationic solution at 70°C until the OH/cation molar ratio was equal to 1.9. The intercalant solution was added to the clay suspension under stirring. The final ( Al+Fe) /clay ratio was equal to 3.8 mmol/g of dry clay. After aging for 24h, the pillared clay precursor was washed until total elimination of chloride ions, dried at 60°C and finally calcined at 500°C for 5h. The resulting material is (Al-Fe)PILC. 

Matthews and Riley [99] preconcentrated iodide by co-precipitation with chloride ions. This is achieved by adding 0.23 g silver nitrate per 500 ml of seawater sample. Treatment of the precipitate with aqueous bromine and ultrasonic agitation promote recovery of iodide as iodate which is caused to react with excess iodide under acid conditions, yielding I3. This is determined either spectrophotometrically or by photometric titration with sodium thiosulfate. Photometric titration gave a recovery of 99.0 0.4% and a coefficient of variation of 0.4% compared with 98.5 0.6% and 0.8%, respectively, for the spectrophotometric procedure. 

The secondary amine function of dobutamine hydrochloride may be determined by potentiometric titration with perchloric acid using glacial acetic acid as a nonaqueous solvent. Mercuric acetate is used to tie up the chloride ion. 

In Nebraska, state regulations require that the chemical makeup of animal feed sold in the state be accurately reflected on the labels found on the feed bags. The Nebraska State Agriculture Laboratory is charged with the task of performing the analytical laboratory work required. An example is salt (sodium chloride) content. The method used to analyze the feed for sodium chloride involves a potentio-metric titration. A chloride ion-selective electrode in combination with a saturated calomel reference electrode is used. After dissolving the feed sample, the chloride is titrated with a silver nitrate standard solution. The reaction involves the formation of the insoluble precipitate silver chloride. The electrode monitors the decrease in the chloride concentration as the titration proceeds, ultimately detecting the end point (when the chloride ion concentration is zero). 

Thioetherification of PECH is feasibly performed in DA-solvents as already described in the patent (20J. For example, the highest substitution was obtained by the reaction of P(ECH-EO)(1 1 copolymer of epichloro-hydrin and ethylene oxide) and equimolar thiophenoxide in HMPA at 100°C for 10 h as DS 83% for sodium and 93% for potassium salts. The DS in our nucleophilic substitution was estimated by the elemental analysis as well as the titration of liberated chloride ion with mercuric nitrate (21). In the latter method, reacted medium was pretreated with hydrogen peroxide when the reductive nucleophiles which can react with mercuric ion were used. As described before for PVC, thiolation was also achieved conveniently with iso-thiuronium salt followed by alkaline hydrolysis without the direct use of ill-smelling thiolate. The thiolated PECH obtained are rubbery solids, soluble in toluene, methylene chloride, ethyl methyl ketone and DMF and insoluble in water, acetone, dioxane and methanol. 

To compare the reactivities of various nucleophiles, the reactions of PECH with equimolar amounts of nucleophiles were carried out at 90°C for 16 h in DMF and the conversion was estimated by titration of chloride ion liberated. The results were summarized in Table 1. The reactivity of S-nucleophile is high as in general. The xanthate obtained was soluble in DMF, but insolubilized gradually on drying. Photosensitive PECH-N, is obtained in good yield notwithstanding the low solubility of sodium azide in DMF. 

We will now look at the relative amounts of ions in solution at the very end of the titration, i.e. after the end point has been reached and surpassed, and note that all of the chloride ion will have been consumed by the precipitation of solid AgCl, and that the addition offurther AgNO3 solution to the reaction solution merely dilutes it. At the end of the titration, we see that [C/ ] [Ag+]. 

Because the major ions are present in nearly constant proportions, the salinity of seawater can be inferred from any of their individual concentrations. The easiest concentration to measure is that of the chloride ion, which is also the most abundant. In practice, this concentration is determined by titrating a sample of seawater with a standardized solution of silver nitrate. The reactions that take place are ... 

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