Acids titration procedure

Successive extraction of the catalytic mixture of XANTHAM affected the recovery of rhodium. Although the overall rhodium recovery was almost quantitative (97%), a retention of activity of 86% was observed when the acidic titration procedure was performed at pH 5-5.5. This result equals the success of PhP(C6H4CH2NEt2)2 [20]. 

Descriptions of sulfuric acid analytical procedures not specified by ASTM are available (32,152). Federal specifications also describe the requited method of analysis. Concentrations of 78 wt % and 93 wt % H2SO4 are commonly measured indirectly by determining specific gravity. Higher acid concentrations are normally determined by titration with a base, or by sonic velocity or other physical property for plant control. Sonic velocity has been found to be quite accurate for strength analysis of both filming and nonfuming acid. 

In this reaction, iodine is liberated from a solution of potassium iodide. This reaction can be used to assess the amount of ozone in either air or water. For determination in air or oxygen, a measured volume of gas is drawn through a wash bottle containing potassium iodide solution. Upon lowering the pH with acid, titration is effected with sodium thiosulfate, using a starch solution as an indicator. There is a similar procedure for determining ozone in water. 

Two excellent methods (utilising acid-base indicators) are available for standardisation. The first is widely employed, but the second is more convenient, less time-consuming, and equally accurate. A third, back-titration, procedure is also available. 

The theory of titrations between weak acids and strong bases is dealt with in Section 10.13, and is usually applicable to both monoprotic and polyprotic acids (Section 10.16). But for determinations carried out in aqueous solutions it is not normally possible to differentiate easily between the end points for the individual carboxylic acid groups in diprotic acids, such as succinic acid, as the dissociation constants are too close together. In these cases the end points for titrations with sodium hydroxide correspond to neutralisation of all the acidic groups. As some organic acids can be obtained in very high states of purity, sufficiently sharp end points can be obtained to justify their use as standards, e.g. benzoic acid and succinic acid (Section 10.28). The titration procedure described in this section can be used to determine the relative molecular mass (R.M.M.) of a pure carboxylic acid (if the number of acidic groups is known) or the purity of an acid of known R.M.M. 

Procedure (iodometric method). Weigh out accurately about 5.0 g of the bleaching powder into a clean glass mortar. Add a little water, and rub the mixture to a smooth paste. Add a little more water, triturate with the pestle, allow the mixture to settle, and pour off the milky liquid into a 500 mL graduated flask. Grind the residue with a little more water, and repeat the operation until the whole of the sample has been transferred to the flask either in solution or in a state of very fine suspension, and the mortar washed quite clean. The flask is then filled to the mark with distilled water, well shaken, and 50.0 mL of the turbid liquid immediately withdrawn with a pipette. This is transferred to a 250 mL conical flask, 25 mL of water added, followed by 2 g of iodate-free potassium iodide (or 20 mL of a 10 per cent solution) and 10 mL of glacial acetic acid. Titrate the liberated iodine with standard 0.1M sodium thiosulphate. 

There are two important hydrogenation (or reduction) — titration procedures for the detn of N as ammonia. The Devarda method involves the quant reduction of nitrates to ammonia in alkaline soln using an Ai-Cu-Zn alloy. The ammonia evolved is distd into standard sulfuric acid... 

Barium perchlorate colorimetric titration. This colorimetric titration procedure is used in the determination of inorganic sulfate impurities in complex systems of water-soluble sulfonates and sulfonic acids. Sulfonates are precipi-... 

The titration procedure used was that described by Ben Yaakov et al. [9], in which 100 ml of seawater or brine sample is titrated in 30-50 burette increments with 3 - 5 ml standard 0.1 M hydrochloric acid using a pH electrode. 

A computer program has been used to calculate the magnitude of systematic errors incurred in the evaluation of equivalence points in hydrochloric acid titrations of total alkalinity and carbonate in seawater by means of Gran plots. Hansson [13] devised a modification of the Gran procedure that gives improved accuracy and precision. The procedure requires approximate knowledge of all stability constants in the titration. 

Carpenter et al. [3] proposed that, in order to overcome this difficulty, higher acidity and higher potassium iodide concentrations or a back titration procedure should be used. 

Procedure Weigh accurately about 0.4 g and dissolve in a mixture of 40 ml of alcohol and 10 ml of 0.01 N hydrochloric acid. Titrate the resulting mixture with 0.1 N iodine solution till a yellow colour that... 

Procedure Weigh accurately about 0.2 g of sodium metabisulphite and dissolve in 50.0 ml of 0.1 N iodine solution and add 1 ml hydrochloric acid. Titrate the excess of iodine with 0.1 N sodium thiosulphate employing freshly prepared starch solution, added towards the end of the titration, as indicator. Each ml of 0.1 N iodine is equivalent to 0.0047453 g of Na Oj. 

Polymer Solubility. The modified polymers were soluble in DMSO, dimethylacetamide, dimethylformamide and formic acid. They were insoluble in water, methanol and xylene. Above about 57% degree of substitution, the polymers were also soluble in butyrolactone and acetic acid. Solubility parameters were determined for each polymer by the titration procedure as described in the literature (65). The polymer was dissolved in DMSO and titrated with xylene for the low end of the solubility parameter and a second DMSO solution was titrated with water for the high end of the solubility parameter range. These solubility parameters and some other solubility data are summarized in Table II. 

The procedure called titration can be used to standardize a solution of a base, which means determine its molar concentration. To standardize a base, a solution of the base with unknown molarity is gradually added to a solution containing a known mass of an acid. The procedure enables you to determine when the number of moles of added OH- ions from the base equals the number of moles of H+ ion from the acid. 

Potentiometric titration is actually a form of the multiple known subtraction method. The main advantage of titration procedures, similar to multiple addition techniques in general, is the improved precision, especially at high determinand concentrations. ISEs are suitable for end-point indication in all combination titrations (acid-base, precipitation, complexometric), provided that either the titrand or the titrant is sensed by an ISE. If both the titrant and the titrand are electro-inactive, an electrometric indicator must be added (for example Fe ion can be titrated with EDTA using the fluoride ISE when a small amount of fluoride is added to the sample solution [126]). 

M Mg(OH)2. This problem gives you Step 6 in the titration procedure and asks you to back-solve for the molarity of the base. Start by finding the number of moles of acid present in the solution by multiplying the molarity (0.50 M) by the volume (0.005 L), giving you 0.0025 mol. Next, examine the balanced neutralization reaction to determine the number of moles of mc -nesium hydroxide needed to neutralize 0.0025 mol HNO2 ... 

The residual double bonds of poly(methyl acrylate) have been determined by bromination [9,27]. Bromination is accomplished through the addition of potassium bromide to potassium bromate in acidic medium [9]. Styrene-butadiene copolymers contain residual double bonds. The butadiene content of the copolymer has been determined by an iodine monochloride titration procedure [9],... 

The acidic nature of the SiO2 (AI2O3) catalysts over the whole range was explored by Thomas (78) using a titration procedure with potassium hydroxide as neutralizer. A general relationship was observed between the amount of catalytic cracking and acidity. His method of determining the acid nature of the catalyst has been criticized by Miesserov (79) whose work indicated that NaOH solutions reacted with other protons... 

Procedure. Transfer 0.6 to 0.8 g of the dry sample weighed to 0.1 mg to a 100 ml beaker. Add 50 ml of 25 percent acetic acid soln and stir to dissolve. Transfer to a 250 ml volumetric flask and dilute to the mark. Attach the cylinder of oxygen-free carbon dioxide to the titration flask as shown in Fig 1 and allow the gas to flow for 5 minutes thru gas humidifier (H) to displace the air. Continue the flow of gas during the-entire titration procedure, pipet a 25 ml aliquot of the solution of the sample into the titration flask (Fig 2). Add 30 ml of 20% Na acetate soln and 20.00 ml of 0.2N titanous chloride soln and swirl the flask for about 20 secs. 

Replacement of sulfuric acid by perchloric acid as described in the distillation-titration procedure given below gave satisfactory results... 

Total Acid. Simple titration procedures are used to determine total acidity. Problems arise because of the widely varying amounts of different acids in wines tartaric, malic, citric, lactic, succinic, acetic, etc. Different pKtt values for these acids make it impossible to predetermine easily the correct pH of the endpoint. Since a strong base is being used to titrate relatively weak acids, the endpoint will be greater than pH 7. In this country phenolphthalein (8.3) or cresol red (7.7) endpoints or a pH meter to 9.0 have been used (3, 6, 12, 76, 77) and the results are expressed as tartaric acid. The result at pH 7.7 X 1.05 approximately equals the result of titrating to pH 8.4. In Europe pH 7 is usually the endpoint, in France the results are expressed as sulfuric acid, and in Germany as tartaric or in milliequivalents (78). 

Errors may occur in the Gran titration procedure if weakly acidic species with dissociation constants (expressed as pKd) in the range of the extract pH are present. In particular, curvature or reduction (or both) of the slope of the Gran exponential plot results (24), because weak acid dissociation and titration of released free acidity take place during the portion of the titration used for end-point determination. Fortuitously, some of the common, weak carboxylic acids (e.g., formic and acetic) are not stable toward microbial decomposition when collected in aerosol samples from the atmosphere, so much of the historical data base on strong acid content of aerosols does not suffer from this positive error source, unless of course the microbial processes produce additional strong acids. 

Phillips, M. F. Gaffney, J. S. Goodrich, R. W. Tanner, R. L. Computer-Assisted Gran Titration Procedure for Strong Acid Determination Brookhaven National Laboratory Upton, NY, 1984 Report BNL 35734. 

The reaction of DCIP with ascorbic acid is shown in Figure El 1.3. Ascorbic acid reduces the indicator dye from an oxidized form (red in acid) to a reduced form (colorless in acid). The procedure is simple, beginning with dissolution of the sample to be tested in metaphosphoric acid. An aliquot of the sample is then titrated directly with a solution of DCIP. Although the original DCIP solution is blue, it becomes light red in the acid solution. Upon reaction with ascorbic acid in the sample, the dye becomes colorless. Titration is continued until there is a very slight excess of dye added (faint pink color remains in the acid solution). 

A non-aqueous differentiating titration procedure (39) involves passage of the artificial sweeteners mixture through a cationic exchange resin, Dowex 50-X8, to separate and convert saccharin to its acid form. The solution obtained is titrated potentiometrically in methyl isobutyl ketone with 0.1 N sodium methoxide. The method has been applied in presence of cyclamate and benzyl alcohol. 

Coulometric titration procedures have been developed for a great number of oxidation-reduction, acid-base, precipitation, and complexation reactions. The sample systems as well as the electrochemical intemediates used for them are summarized in Table 4.1, and indicate the diversity and range of application for the method. An additional specialized form of coulometric titration involves the use of a spent Karl Fischer solution as the electrochemical intermediate for the determination of water at extremely low levels. For such a system the anode reaction regenerates iodine, which is the crucial component of the Karl Fischer titrant. This then reacts with the water in the sample system according to the... 

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