Measurements excess

Chlorate Analysis. Chlorate ion concentration is determined by reaction with a reducing agent. Ferrous sulfate is preferred for quaHty control (111), but other reagents, such as arsenious acid, stannous chloride, and potassium iodide, have also been used (112). When ferrous sulfate is used, a measured excess of the reagent is added to a strong hydrochloric acid solution of the chlorate for reduction, after which the excess ferrous sulfate is titrated with an oxidant, usually potassium permanganate or potassium dichromate. 

Oxalate Acid Number. A metal soap solution is treated with a measured excess of organic acid. Potassium oxalate solution is added to precipitate the metal and the total sample is back-titrated with alkaU to determine its acidity. Acidity is expressed ia acid number units, equivalent to mg KOH per g. A neutral soap gives a 2ero acid number, an acidic soap solution a positive acid number, and a basic soap solution a negative acid number. 

Let this volume correspond to V mL 1M HC1. To another sample, a measured excess of standard 0.1M sodium hydroxide (free from carbonate) over that required to transform the hydrogencarbonate to carbonate is added ... 

The sulphate is precipitated as barium sulphate from acid solution, the precipitate is filtered off and dissolved in a measured excess of standard EDTA solution in the presence of aqueous ammonia. The excess of EDTA is then titrated with standard magnesium chloride solution using solochrome black as indicator. 

Assay Methods. A Na carbonate fusion prod is currently used for assay of mil grade AP (see below under Specifications), but recently attempts have been made to replace it with a method which is faster and simpler to carry out. Two procs have been proposed a) Titanous Chloride Titration. A measured excess of Ti trichloride is added to a known weight of AP which reacts according to the equation ... 

From the physical point of view there cannot exist, under equilibrium conditions, a measurable excess of charge in the bulk of an electrolyte solution. By electrostatic repulsion this charge would be dragged to the phase boundary where it would be the source of a strong electric field in the vicinity of the phase. This point will be discussed in Section 3.1.3. 

Figure 2 shows measured excess enthalpies for aqueous phases and two-phase mixtures of n-butoxyethanol/water at 55.0 °C. Data from four replicate additions of 2 cm3 of butoxyethanol to water are shown in Figure 2a Figure 2b shows data from the subsequent addition of an additional 2 cm3 of butoxyethanol to each of the solutions of Figure 2b. 

Figure 4. Measured excess enthalpies for the amphiphilic side of the n-butanol/water diagram at 55.0 °C compared to results from the literature.(14,16) (Symbols same as for Fig. 3.)...

However, the titrations must begin with the neat compound, if one desires to measures excess enthalpies referred to a single-compound standard state. In this case the number of experiments and the data... 

If the analyte metal ion forms a stable EDTA complex rapidly, and an end point can be readily detected, a direct titration procedure may be employed. More than thirty metal ions may be so determined. Where the analyte is partially precipitated under the reaction conditions thereby leading to a slow reaction, or where a suitable indicator cannot be found, back titration procedures are used. A measured excess of EDTA is added and the unreacted EDTA titrated with a standard magnesium or calcium solution. Provided the analyte complex is stronger than the Ca-EDTA or Mg-EDTA complex a satisfactory end point may be obtained with eriochrome black T as indicator. An alternative procedure, where end points are difficult to observe, is to use a displacement reaction. In this case, a measured excess of EDTA is added as its zinc or magnesium complex. Provided the analyte complex is the stronger, the analyte will displace the zinc or magnesium. 

In this work, halogens were added across the double bonds of unsaturated fatty acids (commercial available sunflower oil) to form addition compounds and the degree of uptake was measured. A measured excess of iodine monobrontide (IBr) was allowed to react with the oil in the dark. At the end of a timed period, an excess of K1 was added to convert the remaining IBr to The 1 formed was then titrated with standard thiosulfate. This was a back-titration method. A back-titration blank was also required, where the sample was omitted. The uptake of iodine was calculated... 

Comelli, F. and Francesconi, R. Isothermal vapor-liquid equilibria measurements, excess molar enthalpies, and excess molar volumes of dimethyl carbonate + methanol. + ethanol, and propan-l -ol at 313.15 K. J. Chem. Eng. Data, 42(4) 705-709, 1997. 

As discussed in Section II, measured excess scattering intensity, after a melt is cooled below its melting point, increases exponentially with time at all scattering wavevectors and the inverse of niax (at which intensity is a maximum) diverges as These observations are similar to those... 

Elemental composition S 25.23%, H 0.79%, N 11.02, 0 62.95%. Nitrosylsulfuric acid may be analysed by IR, NMR and mass spectrometry, as well as by elemental microanalysis. Wet analysis involves hydrolyzing the compound in the presence of excess NaOH and measuring excess base by potentiometric titration. 

Elemental composition K 28.22%, Cl 25.59%, and 0 46.19%. An aqueous solution is analyzed for potassium by AA, ICP, and other methods (see Potassium). Perchlorate ion may be analyzed by ion chromatography or a liquid-membrane electrode. Iodide, bromide, chlorate, and cyanide ions interfere in the electrode measurement. Alternatively, perchlorate ion may be measured by redox titration. Its solution in 0.5M H2SO4 is treated with a measured excess standard ferrous ammonium sulfate. The excess iron(II) solution is immediately titrated with a standard solution of potassium dichromate. Diphenylamine sulfuric acid may be used as an indicator to detect the end point ... 

Saponification Titrations. Weighed aliquots of oxidation products (0.1-0.5 grams) were titrated with ethanolic potassium hydroxide (0.2N) in aldehyde-free ethanol to a phenolphthalein end point while nitrogen was passed in. A measured excess of alkali was then added, and the solution was boiled for 15 minutes with nitrogen slowly passing through. Back-titration with standard HC1 gave the amount of alkali consumed by saponification. 

Save the filter paper with residue for Zr detn. Fill the volumetric flask to the mark and pipet a 50-ml aliquot into a 400-ml beaker for the chromate detn. Dilute to 250 ml, and add 10 ml of dilute sulfuric acid (1 4) and 10 ml of phosphoric acid (1 1). Add a measured excess consisting of ca 30 ml of standardized 0.05N ferrous ammonium sulfate soln and 6 to 8 drops of Na diphenylamine sulfonate indicator soln (0.2 g in 100 ml of w). Titrate the excess ferrous iron with 0.05N std K dichromate soln, adding the dichromate slowly with stirring, until the pure grn color changes to gray-grn. Then add the dichromate one drop at a time until the first tinge of purple or violet-blue appears... 

In this method the sample is reacted with a measured excess of aq KOH, using isopro-panol as a mutual solvent, if required (but not for EtAcet). The amt of KOH consumed, which is detd by titrating tbe excess with std mineral acid, is a measure of the ester originally present. Since this detn is based on acidimetric... 

Quantitative studies for the formation of adducts from 5-membered heteroaromatic rings and methoxide ion have usually been carried out in methanolic solution and, in some cases (pyrrole derivatives), in Me2SO-MeOH 2 1 (v/v). Data have been obtained by allowing the substrates to react with a measured excess of MeO" and by following the increase in absorbance of the adduct. The observed pseudo first-order rate constant for the attainment of the equilibrium is found to obey the relation given in Eq. (23),... 

An electrometric method for determining soluble sulphates consists in precipitation of the latter by the addition of a measured excess of a standard solution of lead nitrate in the presence of alcohol, removing the lead sulphate by filtration, washing it with alcohol, and titrating the unchanged lead nitrate in the filtrate electrometrically with standard ferroeyanide solution.6... 

K2Cr207 is not as strong an oxidant as KMn04 or Ce4+. It is employed chiefly for the determination of Fe2+ and, indirectly, for species that will oxidize Fe2+ to Fe3+. For indirect analyses, the unknown is treated with a measured excess of Fe2+. Then unreacted Fe2+ is titrated with K2Cr207. For example. CIO7, NOj, Mn04, and organic peroxides can be analyzed this way. Box 16-1 describes the use of dichromate in water pollution analysis. 

Figure 27-5 shows an instrument that measures C, FI, N, and S in a single operation. First, a 2-mg sample is accurately weighed and sealed in a tin or silver capsule. The analyzer is swept with Fie gas that has been treated to remove traces of 02, FI20, and C02. At the start of a run, a measured excess of Oz is added to the He stream. Then the capsule is dropped into a preheated ceramic crucible, where the capsule melts and sample is rapidly oxidized. 

The total hydrocyanic acid is determined similarly, but after the cyanohydrin of benzaldehyde has been decomposed. For this purpose, 100 c.c. of the spirit in a 300 c.c. flask are rendered strongly alkaline with ammonia and then treated with a measured excess of the silver nitrate solution. The whole is shaken, immediately acidified with dilute nitric acid and diluted to the mark, an aliquot part of the filtered liquid being then treated as in the determination of the free hydrocyanic acid. 

The most productive two-phase (H-V or H-Lhc) equilibrium apparatus was developed by Kobayashi and coworkers. The same apparatus has been used for two-phase systems such as methane + water (Sloan et al., 1976 Aoyagi and Kobayashi, 1978), methane + propane + water (Song and Kobayashi, 1982), and carbon dioxide + water (Song and Kobayashi, 1987). The basic apparatus described in Section 6.1.1.2 was used in a unique way for two-phase studies. With two-phase measurements, excess gas was used to convert all of the water to hydrate at a three-phase (Lw-H-V) line before the conditions were changed to temperature and pressures in the two-phase region. This requires very careful conditioning of the hydrate phase to prevent metastability and occlusion. Kobayashi and coworkers equilibrated the hydrate phase by using the ball-mill apparatus to convert any excess water to hydrate. 

The mixture was diluted to a final concentration of 100 nM short strand and 250 nM long strand duplexes for FPA measurement. Excess annealed long strand duplexes can be added to ensure that there is no further increase in anisotropy, as this species does not contain the fluorescence dye. 

A persistent management trend today is the one toward being leaner and meaner than the competition. A measurable excess in human resources is a luxury that is rarely found in todays chemical industry in developed countries. Management must constantly be attuned to the problems of dilution of knowledge by movement of their human assets. 

Mainstream presolar SiC grains are believed to have condensed in the atmospheres of AGB carbon stars and calcium seems consistent with that expectation. Bulk samples show measurable excess of 42Ca/4°Ca ratio, as expected from s-process nucleosynthesis. 

The method of carrying out kinetic runs depends upon the rate of nitration and the temperature. For relatively slow reactions at or near room temperature, the easiest procedure is to carry out the reaction in a volumetric flask to which are added a weighed amount of substrate (—40 mg), sulfuric acid of known composition nearly to the mark, and, finally, a measured excess (—0.5 g) of —70% nitric acid. Urea (one-tenth of the molar concentration of nitric acid) must also be added to prevent nitrosa-tion. The flask is then placed in a thermostatted bath and, at appropriate intervals, portions are removed, quenched, and the optical density measured. For kinetic runs above 50°C the procedure differs only in that aliquots are sealed in Pyrex tubes before thermostatting. 

Other examples of noble gas paleotemperatures have been reported by Rudolph et al. (1983). They calculated temperatures as low as 1-2 °C 22,000 years ago (dated by 14C) in Germany, accompanied by relatively negative <5D and <5lsO values and a measurable excess of radiogenic helium. 

With the decoloration method, it is not possible to reach equally well-defined values for the mixing time. In order to approach this as closely as possible one can, however, add a well-measured excess of decolorizing agent to the batch. Decoloration then occurs at places where the concentration is differed by only, say, +25% from the final step. In this way it is also possible to find mixing times 075, being the time required for the bulk of the liquid to be decolorized. There are, however, parts of the liquid near fixed walls that often do not decolorize, which makes the decolorization method somewhat subjective. However, it can be said that the 9P value approaches the desired value 6r p, with r = p, rather closely, because to bring the concentration in the bulk of the liquid to within +(100 — p)% of the final value, the tracer has to be spread over at least p% of the vessel volume. 

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