Absorption coefficients solutions

Absorption coefficient, linear decaidic a. K Aqueous solution at infinite dilution aq, CO... 

Only slightly less accurate ( 0.3—0.5%) and more versatile in scale are other titration techniques. Plutonium maybe oxidized in aqueous solution to PuO " 2 using AgO, and then reduced to Pu" " by a known excess of Fe", which is back-titrated with Ce" ". Pu" " may be titrated complexometricaHy with EDTA and a colorimetric indicator such as Arsenazo(I), even in the presence of a large excess of UO " 2- Solution spectrophotometry (Figs. 4 and 5) can be utilized if the plutonium oxidation state is known or controlled. The spectrophotometric method is very sensitive if a colored complex such as Arsenazo(III) is used. Analytically usehil absorption maxima and molar absorption coefficients ( s) are given in Table 10. Laser photoacoustic spectroscopy has been developed for both elemental analysis and speciation (oxidation state) at concentrations of lO " — 10 M (118). Chemical extraction can also be used to enhance this technique. 

AT the path length, and P (A) the mass absorption coefficient at wavelength A. Between absorption edges, P (A) is proportional to Z A and is nearly independent of physical or chemical state. An absorption measurement on each side of an absorption edge is required for each element analyzed. X-ray absorption is especially useful in determining heavy elements in mixed materials of lower Z, such as lead in gasoline and uranium in aqueous solution. 

This, as is shown by the theory, is due to the evolution of the heat of absorption, during solute adsorption at the front part of the peak. Conversely, the back of the peak is eluted at a lower temperature than the surroundings throughout the length of the column due to the absorption of the heat of solute desorption. As a result, the distribution coefficient of the solute at the front of the peak, and at a higher temperature, will be less than the distribution coefficient at the back of the peak, at the... 

When 1, 3, 3-triethoxypropene was hydrolyzed with IN sulfuric acid, a solution of malonaldehyde whose optical density was perfectly stable at 350 m/x for at least one week was obtained. If the solution was made alkaline, the optical density at the same wavelength increased by a small value and then remained virtually constant for at least one week (56). It was also observed that in these solutions the extinction coefficient at 350 m/x was very low (observed 8.3, 61.5 and 69, for solutions of pH 0.4, 7.15 and 9.4 respectively) compared with previously reported values which varied from 200 ( 40) to 1000 ( 48). On the other hand, the absorption of solutions having a pH of 3 to 5, increased considerably with time (at pH 4.75, the extinction coefficient of malonaldehyde at 350 m/x was initially about 40 after four weeks a value of about 930 was recorded and the optical density of the solution was still increasing). This increase in absorption was accompanied by a marked decrease in the malonaldehyde content of the solution, as measured by the thiobarbituric acid method. As a corollary, it was found that aqueous solutions of malonaldehyde, prepared by autocatalyzed hydrolysis (33) of the same acetal and which had a pH of about 3.5, showed, at the completion of the hydrolysis, considerably higher extinction coefficient values at 350 m/x than did those malonaldehyde solutions which were prepared by hydrolysis with IN acid and subsequently adjusted to pH 4. It appears, therefore, that at pH values at which most of the periodate oxidations are carried out, malonaldehyde is unstable and undergoes a chemical reaction, the nature of which is not, as yet, known. 

The basic principle of most colorimetric measurements consists in comparing under well-defined conditions the colour produced by the substance in unknown amount with the same colour produced by a known amount of the material being determined. The quantitative comparison of these two solutions may, in general, be carried out by one or more of six methods. It is not essential to prepare a series of standards with the spectrophotometer the molar absorption coefficient can be calculated from one measurement of the absorbance or... 

The values of the molar absorption coefficients and e2 can be deduced from measurements of the absorbances of pure solutions of substances 1 and 2. By measuring the absorbance of the mixture at wavelengths Xl and X2, the concentrations of the two components can be calculated. 

Discussion. The titration of a copper ion solution with EDTA may be carried out photometrically at a wavelength of 745 nm. At this wavelength the copper-EDTA complex has a considerably greater molar absorption coefficient than the copper solution alone. The pH of the solution should be about 2.4. 

Mohr procedure exptl. details of, 349, 351 Molar absorption coefficient 649 Molar conductivity 520 Molar extinction coefficient see Molar absorption coefficient Molar solution definition, 260 Molarity 259 Mole 259... 

Specific absorption coefficient 650 Specific gravities solutions of acids, (T) 829 of selected reagents (T), 829 Spectral half bandwidth 663 Spectrofluorimetry 731 Spectrograph adjustment of, 771 commercial instruments, 761, 775, 776 Spectrographic analysis see Emission spectrographic analysis... 

Properties of luciferin. The crystals are microscopic needles, which melt with decomposition at 205-210°C (Bitler and McElroy, 1957). It is a quite stable luciferin compared with some other luciferins, such as Cypridina luciferin and the luciferins of krill and dinoflagellates. It is not significantly affected by lOmM H2SO4 and lOmM NaOH at room temperature in air. The absorption spectral data of luciferin are shown in Fig. 1.3 (McElroy and Seliger, 1961). The molar absorption coefficient of the 328 nm peak in acidic solutions and that of the 384 nm peak in basic solutions are both 18,200 (Morton et al., 1969). Luciferin is fluorescent, showing an emission maximum at 537 nm in both acidic and basic conditions, although the intensity of the fluorescence is lower in acidic solution than in basic solution (fluorescence quantum yields 0.62 in basic condition, and 0.25 in acidic condition Morton et al., 1969). The chemical synthesis... 

Deviations from Henry s law are exhibited by most gases having absorption coefficients greater than 100. In some cases the discrepancies vanish at higher temperatures. Thus Roscoe and Dittmar (1860) found that ammonia did not follow the law of Henry at the ordinary temperature, but Sims (1862) showed that the deviations from the law became less as the temperature at which absorption occurred increased, until at 100° the amount of ammonia dissolved by water was directly proportional to the pressure. The deviations appear to be always greatest under small pressures, and to decrease with increasing pressure, and therefore with increasing concentration of the solution they are doubtless due to chemical interaction between the solvent and dissolved gas. 

The absolute values of the solubilities of gases are not at present calculable from any general law, although W. M. Tate (1906) finds in the case of aqueous solutions a relation with the viscosities of the solution (/x ), and water (/x0), the critical temperatures of the gas (T0), and of water (T. ), and the absorption coefficients ... 

Yoshida and Akita (Yl) determined volumetric mass-transfer coefficients for the absorption of oxygen by aqueous sodium sulfite solutions in counter-current-ffow bubble-columns. Columns of various diameters (from 7.7 to 60.0 cm) and liquid heights (from 90 to 350 cm) were used in order to examine the effects of equipment size. The volumetric absorption coefficient reportedly increases with increasing gas velocity over the entire range investigated (up to approximately 30 cm/sec nominal velocity), and with increasing column diameter, but is independent of liquid height. These observations are somewhat at variance with those of other workers. 

Carotenoid concentration in solution can be calculated taking in consideration the absorption coefficient (Aj ) or molar absorptivity (s) values of the specific carotenoid according to the Beer-Lambert law. The absorption coefficient and e values were determined for many carotenoids and values are available in the literature. These two values are related as shown in Equation 1. The concentration is calculated according to Equation 2. 

The metal formed is deposited on the colloidal particles and causes the absorption of the solution to increase at all wavelengtlK. The depositel cadmium is very reactive. It is reoxidized when air is admitted to the illuminated solution. Addition of methyl viologen to the illuminated solution under the exclusion of air yields the blue colour of the semi-ceduced methyl viologen, MV". As the absorption coefficient of MV" is known, the concentration of reduced cadmium can be readily calculated. reoxidises cadmium atoms ... 

Meyer-Dulheuer [55] has analysed the pure additives (phenolic antioxidants, benzotriazole UV stabilisers and HALS compounds) of Table 9.8 in THF solutions by means of MALDI-ToFMS. As it turns out, polar molecules in the mass range of below 800 Da, which have a high absorption coefficient at the laser wavelength used, can often be measured without any matrix [55,56]. In this case, there is no matrix-assisted laser desorption and ionisation (MALDI) process any more. It is a simple laser desorption/ionisation (LDI) process. The advantage of this method is a matrix-free mass spectrum with the same mass resolution as in the MALDI case,... 

We have also measured the rate constant for the association reaction of two Mn(C0)5 radicals generated on photolysis of Mn2(CO)io- With appropriate assumptions regarding the absorption coefficient for Mn(C0)5, the rate constant for this reaction was determined to be (2.7 0.6) x 10 1 mole l s [6,10]. This is compatible with the diffusion limited rate constant for this reaction that has been measured in solution and is within an order of magnitude of a gas kinetic rate constant as would be expected for an essentially unactivated radical-radical association reaction [33a]. 

Tab. 4.5 Singlet excitation energies of a small subset of psoralen compounds. Experimental data in aqueous solution given in parentheses [99]. Experimental absorption coefficients are denoted w=weak (<8000), i = intermediate (8000-15000), and s = strong (>15000).

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