Measurements by Titration

Corrosion measurements by titration (CMT) were first introduced in 1990. The method is based on the following considerations When a metal corrodes with no applied current in an aqueous solution, the anodic dissolution reaction 

This shows that the number of hydrogen ions used in cathodic reactions is equal to the number of charges transferred in the anodic reaction. The pH value in the solution can then be maintained constant by a pH stat, controlling the addition of acid to the solution at such a rate that the loss of hydrogen ions is compensated. Then the following condition is fulfilled  

Because of (1), measurements can be made at short intervals, virtually continuously. 

The measurements present the rate directly without extended mathematical analysis and interpretation. 

The CMT method is based on the direct measurement of chemical change, and a number ofrestrictions may arise due to the chemistry of the corrosion reactions and the electrolyte solution. The simple relation (4) in accordance with reactions (l)-(3) is not always valid because of complications connected with either the anodic or the cathodic reactions. 

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The solvent can contain traces of acidic or basic compounds which are measured by titration. 

Figure V-8 illustrates that there can be a pH of zero potential interpreted as the point of zero charge at the shear plane this is called the isoelectric point (iep). Because of specific ion and Stem layer adsorption, the iep is not necessarily the point of zero surface charge (pzc) at the particle surface. An example of this occurs in a recent study of zircon (ZrSi04), where the pzc measured by titration of natural zircon is 5.9 0.1...

Various methods can be used to analy2e succinic acid and succinic anhydride, depending on the characteristics of the material. Methods generally used to control specifications of pure products include acidimetric titration for total acidity or purity comparison with Pt—Co standard calibrated solutions for color oxidation with potassium permanganate for unsaturated compounds subtracting from the total acidity the anhydride content measured by titration with morpholine for content of free acid in the anhydride atomic absorption or plasma spectroscopy for metals titration with AgNO or BaCl2 for chlorides and sulfates, respectively and comparison of the color of the sulfide solution of the metals with that of a solution with a known Pb content for heavy metals. 

The concentration of acids or acidic salts in solution that can be measured by titration with a standard alkali to a selected pH endpoint. 

The lodini concentration is then measured by titration with sodium thiosulfate ... 

Procedure. Concentration of n-BuLi in the feed was measured by titration (15). The reactor was filled completely with styrene monomer solution in toluene initially. Time was measured from the moment initiator and monomer feed was initiated. The reaction was... 

The charge of a number of proteins has been measured by titration. The early experimental work focused on the determination of charge as a function of pH later work focused on comparing the experimental and theoretical results the latter obtained from the extensions of the Tanford-Kirkwood models on the electrostatic behavior of proteins. Ed-sall and Wyman [104] discuss the early work on the electrostatics of polar molecules and ions in solution, considering fundamental coulombic interactions and accounting for the dielectric properties of the media. Tanford [383,384], and Tanford and Kirkwood [387] describe the development of the Tanford-Kirkwood theories of protein electrostatics. For more recent work on protein electrostatics see Lenhoff and coworkers [64,146,334]. 

Marsh grapefhiit (MGF) pulp was homogenized in 5 volumes of extraction buffer at 4 C and maintained at pH 8.0 (28). The homogenate was stirred for one hour, centrifuged and the supernatant used as the PE extract. Activity was measured by titration with a Brinkman (Westbury, NY) pH stat titrator at pH 7.5 and 30°C in 25 mL of 1 % high methoxyl pectin (Citrus Colloids Limited, Hereford, UK) with O.IM NaCl. PE units are expressed as the microequivalents of ester hydrolysed per minute. Uronic acid analyses were conducted based on the m-phenyl phenol (4) as modified for microplate reading (30). 

In a typical test 750 mg of catalyst was added to a continuous stirred tank reactor containing the nitrate ions in 1 L of phosphate buffer solution. This suspension contained 85% H3PO4 (331 g), NaNOs (198 g), NaOH (84g), and Ge02 dissolved in water and was stirred under a H2 flow of 150 L/h. The amonnt of hyam formed and selectivity after 90 min at 30°C were measured by titration [2-3]. Catalysts A and C were also chosen for stndying the effect of Pd loading and Pt addition. 

Fig. 2 Progress of hyperbranched poly(acrylic acid) graft formation on smooth gold films as measured by ellipsometry ( ) or on polyethylene powders as measured by titration ( ) of the supported - CO2H groups...

Water extraction or dilution of fresh material. Alkaline steam distillation with final measurement by titration. 

NH4CN may be analyzed by heating the salt and trapping the decomposed products HCN and ammonia in water at low temperatures. The aqueous solution is analyzed for cyanide ion by silver nitrate titrimetric method or an ion-selective electrode method and ammonia is measured by titration or electrode technique (Patnaik, P. 1997. Handbook of Environmental Analysis, Boca Raton, FL Lewis Publishers). 

Elemental composition H 4.11%, Mo 48.94%, N 14.29% O 32.65. (NH4)2Mo04 is digested with nitric acid and the molybdenum metal is analyzed by atomic absorption or emission spectrophotometry. It is dissociated to ammonia, which may be measured by titration or by an ion-specific electrode technique (see Ammonia). Ammonium molybdate reacts under acid conditions with dilute orthophosphate solution to form molybdophosphoric acid which, in the presence of vanadium, forms yellow vanadomolybdophosphoric acid the intensity of the yeUow color may be measured by a spectrophotometer at 400 to 490 nm and is proportional to the trace amount of ammonium molybdate. 

The B2O3 content of borax may be determined by extraction into HCl solution followed by complexation with mannitol and titration with dUute NaOH. The Na20 content of horax may he measured by titration of an aqueous solution with dUute HCl. Boron and sodium metals in the acid extract of horax may be analyzed by atomic absorption or emission spectroscopy after appropriate dUution of the extract. In the solid phase B2O3 and Na20 may he measured nondestructively by x-ray techniques. 

Elemental composition Co 45.39%, Cl 54.61%. Aqueous solution of the salt or acid extract may be analyzed for cobalt by AA, ICP, or other instrumental techniques following appropriate dilution. Chloride anion in the aqueous solution may be measured by titration with silver nitrate using potassium chromate indicator, or by ion chromatography, or chloride ion-selective electrode. 

Elemental composition H 1.25%, Br 98.75%. The normality of the acid may be measured by titration against a standard solution of a base using a suitable color indicator or by potentiometric titration. The bromide ion, Br, may be measured quantitatively by ion chromatography after appropriate dilution. Concentration of HBr gas in air may be measured by passing a known volume of air through water and determining concentration of acid in aqueous solution by titration or ion chromatography. Alternatively, HBr gas may be analyzed by GC or GC/MS. A very polar column should be used for such measurements. An FID or a TCD type detector may be used for GC analysis. 

Elemental composition H 5.04%, F 94.96%. The total acidity of an aqueous HF solution may be measured by titration with a standard solution of base using phenolphthalein or another suitable color indicator. Alternatively, the end point may be determined by potentiometric titration. The fluoride ion may be analyzed using a fluoride ion-selective electrode or by ion chromatography. The HF gas may be analyzed by GC/MS using a GC column having... 

Elemental composition Fe34.43%, Cl 65.57%. The compound may he identified by x-ray methods. Iron may be analyzed by various instrumental techniques (See Iron). Chloride in the aqueous solution of the compound may be measured by titrating with a standard solution of sdver nitrate or mercuric nitrate or by ion chromatography. 

Elemental composition (anhydrous MgCE) Mg 25.54%, Cl 74.46%. Aqueous solution of the salt may he analyzed for Mg hy AA or ICP method (See Magnesium). The chloride ion can he identified hy ion chromatography or measured by titration with a standard solution of silver nitrate using potassium chromate as indicator. 

Elemental composition Mn 63.19%, 0 36.81%. The pure oxide may be characterized by x-ray crystallography. The Mn02 content in pyrolusite may be measured by titration. An excess of a standard solution of oxalic acid is added to a solution of Mn02 in sulfuric acid. After all solid Mn02 dissolves, the excess oxalic acid is measured by titrating against a standard solution of potassium permanganate (see Reactions). 

Nitryl chloride may he identified by its mass spectra. The characteristic mass ions are 81, 83, 46, 35, and 37. Alternatively, nitryl chloride maybe identified from its physical and chemical properties (See Reactions). The wet analytical method involves treatment with an excess solution of NaOH and titrating the excess NaOH with a standard solution of H2SO4. Alternatively, nitryl chloride is decomposed in water, and the acids HNO3 and HCl formed are measured by titration or the NO and CH determined by ion specific electrodes or ion chromatography. 

Elemental composition K 30.51%, C18.75%, H 0.79% O 49.95%. An aqueous solution of potassium hydrogen phthalate may be measured by titration against a standard solution of potassium hydroxide. 

An acidic solution of tellurium (IV) or tellurium (VI) is treated with sulfur dioxide and hydrazine hydrochloride. Tellurium precipitated from solution can be estimated by gravimetry. Selenium interferes with this test. A volumetric test involves converting tellurium to tellurous acid and oxidizing the acid with excess ceric sulfate in hot sulfuric acid in the presence of Cr3+ ion as catalyst. The excess ceric sulfate is measured by titration with a standard solution of ferrous ammonium sulfate. 

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