Of iodine vapor

When the pyrolysis gases are quenched with a molar excess of iodine vapor, a yield of greater than 50% -xylylene diiodide is recovered. The observation of this effect offered the first direct chemical support for the idea that DPX pyrolysis results in PX (1) (3). 

At a given temperature, the pressure of iodine vapor is constant, independent of the amount of solid iodine or any other factor. The equilibrium constant expression is... 

Chromium can b e deposited by the py roly si s of the iodi de, whi ch i s prepared in situ by passing a flow of iodine vapor over the metal at700°C. The iodide is then decomposed at 1000°C at pressures up to 1 atm as follows ... 

Note The iodine evaporates relatively quickly from the layer after a chromatogram has been removed from the iodine chamber. This evaporation of the iodine can be considerably delayed by covering the chromatogram with a glass plate the edge can also be sealed with adhesive tape, if necessary. Iodine solution can also be used for detection instead of iodine vapor. 

The gas phase detection of iodine vapor with an electrochemical probe has been investigated [195]. The Ag AgI Au electrochemical cell was observed to be sensitive to interference from both oxygen and humidity. A sensor based on a Ag Ag(Cs)I graphite electrode system has been reported by Sola etal. [196]. Temperature effects were studied and the effect of Csl doping of the Agl explored to widen the working temperature range. 

To observe the transient spatiotemporal structure of the WP interference, we have performed the fs pump-fs probe experiment [37], The sample gas was prepared by molecular jet expansion of the mixture of iodine vapor and Ar buffer gas into a vacuum chamber. A continuous gas jet is preferable when we use a high-repetition-rate laser system. The estimated vibrational temperature was 170K[37]. 

Excited State Lifetimes and Bimolecular Quenching of Iodine Vapor 21... 

The reactivity of a double bond, even in a polymer, is strong enough to authorize a lot of reactions (H2, 03...). We paid a special attention to the reaction of iodine vapor as it is a simple reaction for the IR identification of double bond bands in a polymer. As example, we can see on fig. 7 that bands associated with the double bond of ENB residue in EPDM can be identified at 3040, 1685, 808 and 540 cm"1 the last two bands being assi-... 

Exercise 28-8 The vapor-phase photochemical decomposition of 2-propanone proceeds in the presence of iodine vapor, but the amount of carbon monoxide formed becomes very small, Explain how this result argues against the one-step process,... 

FIGURE 6.18 The variation of the molar heat capacity of iodine vapor at constant volume. Translation always contributes rotation contributes except at very low temperature, and vibrations of the molecule contribute at very high temperatures. When the molecules dissociate, the heat capacity becomes very large, but then settles down to a value characteristic of 2 mol I atoms undergoing only translational motion. 

The diffusion coefficient of iodine vapor between 14 and 30°C varies between 0.0767 to 0.0851 (29). The latent heat of fusion of molecular iodine has been found to be 15.66 d= 0.08 kJ/mol (3.74 d= 0.02 kcal/mol), and the latent heat of vaporization, calculated from vapor pressure data, to be... 

Dimethyliodoarsine (m.p. ca. —35° b.p. 154 to 160°) is a yellow oil of penetrating odor, soluble in organic solvents but insoluble in water. It is volatile with steam and inflames when heated in air with the liberation of iodine vapors. Dimethyliodoarsine is decomposed by both nitric and sulfuric acids with the separation of iodine. 

The open end of the reaction tube is attached to an oil pump through a dust trap, and dry nitrogen is admitted at a rate such that the pressure is maintained at or below 25 mm. The bismuth(III) iodide is sublimed into the receiver end of the tube by heating with the spread burner flame and with an auxiliary Tirrill burner adjusted to maximum heat. Satisfactory progress of the sublimation is indicated by the persistence of yellowish-brown bis-muth(III) iodide vapors and by the absence of the violet color of iodine vapor. When the sublimation is complete, the tube is allowed to cool to room temperature in nitrogen at atmospheric pressure. The product is scraped from the receiver section of the tube and stored out of contact with the atmosphere. The yield is 72% based on bismuth. Anal. Calcd. for Bil3 Bi, 35.44. Found Bi, 35.42. The same result is found upon analysis of a resublimed sample of this product. 

Temperature Dependence of Molar Absorption Coefficient of Iodine Vapor at 520 nm... 

The net absorbance is related to the concentration c and the pressure p of iodine vapor in the cell as follows (assuming the perfect-gas law) ... 

TABLE 2 Molar absorption coefficients of iodine vapor at A = 520 nm ... 

Experiment 123. — (a) Free iodine. Add a few drops of carbon bisulphide to a very dilute solution of iodine, made by dissolving a crystal of iodine in a solution of potassium iodide or in alcohol, and observe the color of the carbon bisulphide, which, being much heavier than water, will sink to the bottom of the test tube. How does it resemble the color of iodine vapor ... 

Iodine vapor has characteristic properties. It is violet in color, and it has a characteristic odor. The odor of tincture of iodine (a solution of iodine in alcohol, used as an antiseptic) is a combination of the odor of iodine vapor and the odor of ethyl alcohol. 

Density of iodine vapor.— The arrangement we have just described is exactly that of the cui ves by which Crafts and... 

Disodium phosphate or borax may be used conveniently to buffer a strongly acidic solution to the proper pH value. Sodium bicarbonate is less desirable because of the possible loss of iodine vapor with the escaping carbon dioxide. 

Indications of the feasibility of this approach are to be found in the work of Bowers et al. (2, 3) on the photolysis of iodine vapor in the cavity of an EPR spectrometer, and in the theoretical investigations of Beltran-Lopez et al. on the microwave Zeeman spectra of atomic fluorine and chlorine 1, 8). However, these studies were mainly concerned with the precise determination of atomic g factors to verify the Zeeman theory and involved specialized spectral equipment. The present investigation demonstrates that the spectra of atomic fluorine, chlorine, and bromine are readily observable in commercially available EPR equipment and that reasonable estimates may be made of their concentrations. 

Analyze your product by thin-layer chromatography. Dissolve very small samples of pure ferrocene, the crude reaction mixture, and recrystallized acetylferrocene, each in a few drops of toluene spot the three solutions with microcapillaries on silica gel plates and develop the chromatogram with 30 1 toluene-absolute ethanol. Visualize the spots under a uv lamp if the silica gel has a fluorescent indicator or by adsorption of iodine vapor. Do you detect unreacted ferrocene in the reaction mixture and/or a spot that might be attributed to diacetylferrocene ... 

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