Vapor pressure iodine

A second set of experiments was performed by varying the iodine vapor pressure, using long pulses (1200fs) to blur the vibrational dynamics. In these relatively high-pressure experiments, the PE and RTG decays are identical, and can be fit (see Fig. 2) to the equation ... 

The iodine and the surplus iodide ions combine to give a complex of three iodine atoms with one negative charge, which has an iodine vapor pressure much lower than molecular iodine. The complex decomposes readily if iodine is removed from the system... 

Iodine Pentafluoride. Iodine pentafluoride is a straw-colored Hquid the ir and Raman spectra of the gas phase have been studied (19,46,47) vapor pressure data are given in References 14 and 48. 

The vapor pressure, of soHd iodine has been redetermined using the gas current method and by a static method using a flexible metallic diaphragm (27,28). The data from the gas current method are weU represented by equation 2 (27) ... 

Iodine vapor is characterized by the familiar violet color and by its unusually high specific gravity, approximately nine times that of air. The vapor is made up of diatomic molecules at low temperatures at moderately elevated temperatures, dissociation becomes appreciable. The concentration of monoatomic molecules, for example, is 1.4% at 600°C and 101.3 kPa (1 atm) total pressure. Iodine is fluorescent at low pressures and rotates the plane of polarized light when placed in a magnetic field. It is also thermoluminescent, emitting visible light when heated at 500°C or higher. 

The I2 formed stays in solution, exerting a certain vapor pressure, and is extracted from the brine in a countercurrent air blow-out process. The extracted brine leaves the extraction tower and is discarded or reinjected into the wells to avoid sinking of the soil. The iodine-loaded air is then submitted to a cocurrent desorption process by means of an acidic iodide solution to which SO2 is added. By this solution the iodine is reduced to iodide by the following reaction ... 

Health and Safety Factors and Regulations. Iodine is much safer to handle at ordinary temperatures than the other halogens because iodine is a soHd and its vapor pressure is only 1 kPa (7.5 mm Hg) at 25°C, compared to 28.7 kPa (215 mm Hg) for bromine and 700 kPa (6.91 atm) for chlorine. When handling properly packed containers, usual work clothes are sufficient. In the handling of soHd, unpacked iodine, mbber gloves, mbber apron, and safety goggles are recommended. Respirators or masks are also recommended. 

Lithium Iodide. Lithium iodide [10377-51 -2/, Lil, is the most difficult lithium halide to prepare and has few appHcations. Aqueous solutions of the salt can be prepared by carehil neutralization of hydroiodic acid with lithium carbonate or lithium hydroxide. Concentration of the aqueous solution leads successively to the trihydrate [7790-22-9] dihydrate [17023-25-5] and monohydrate [17023-24 ] which melt congmendy at 75, 79, and 130°C, respectively. The anhydrous salt can be obtained by carehil removal of water under vacuum, but because of the strong tendency to oxidize and eliminate iodine which occurs on heating the salt ia air, it is often prepared from reactions of lithium metal or lithium hydride with iodine ia organic solvents. The salt is extremely soluble ia water (62.6 wt % at 25°C) (59) and the solutions have extremely low vapor pressures (60). Lithium iodide is used as an electrolyte ia selected lithium battery appHcations, where it is formed in situ from reaction of lithium metal with iodine. It can also be a component of low melting molten salts and as a catalyst ia aldol condensations. 

Chlorine heptoxide is more stable than either chlorine monoxide or chlorine dioxide however, the CX C) detonates when heated or subjected to shock. It melts at —91.5°C, bods at 80°C, has a molecular weight of 182.914, a heat of vapori2ation of 34.7 kj/mol (8.29 kcal/mol), and, at 0°C, a vapor pressure of 3.2 kPa (23.7 mm Hg) and a density of 1.86 g/mL (14,15). The infrared spectmm is consistent with the stmcture O CIOCIO (16). Cl O decomposes to chlorine and oxygen at low (0.2—10.7 kPa (1.5—80 mm Hg)) pressures and in a temperature range of 100—120°C (17). It is soluble in ben2ene, slowly attacking the solvent with water to form perchloric acid it also reacts with iodine to form iodine pentoxide and explodes on contact with a flame or by percussion. Reaction with olefins yields the impact-sensitive alkyl perchlorates (18). 

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... 

Consideration of the dissolving of iodine in an alcohol-water mixture on the molecular level reveals the dynamic nature of the equilibrium state. The same type of argument is applicable to vapor pressure. 

Braune and Strassman8 measured the concentration of iodine in gaseous carbon dioxide at pressures up to 50 atm from 32° to 98°C. They passed the carbon dioxide over an excess of solid iodine and analyzed the effluent mixtures. Their pressures were too low to find the saturation vapor pressures or to show whether or not critical end points were formed. 

The stiochiometry of the reaction was measured by reacting Pu metal with a THF solution of C2Rll2 in a sealed, evacuated flank. After 24 hours, volume and pressure measurements showed that 1.46 mm of gas was evolved, after correction for the vapor pressure of THF 1.54 mm of Pu was consumed, and titration of the THF filtrate found 1.8 mm of iodine. The gas composition was not determined, but assuming that the evolved gas was C H, these data indicate that the reaction is ... 

The interhalogen IFT can be made only by indirect routes. For example, xenon difluoride gas can react with iodine gas to produce 1FV and xenon gas. In one experiment xenon difluoride is introduced into a rigid container until a pressure of 3.6 atm is reached. Iodine vapor is then introduced until the total pressure is 7.2 atm. Reaction is then allowed to proceed at constant temperature until completion by solidifying the IF as it is produced. The final pressure in the flask due to the xenon and excess iodine vapor is 6.0 atm. (a) What is the formula of the mterhalogen (b) Write the chemical equation for its formation. 

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 ... 

Black crystaUine solid exists in two modifications stable black needles known as alpha form that produces ruby-red color in transmitted light, and a labile, metastable beta modification consisting of black platelets which appear brownish-red in transmitted light density of alpha form 3.86 g/cm at 0°C density of beta form 3.66 g/cm at 0°C alpha form melts at 27.3°C, vapor pressure being 28 torr at 25°C beta form melts at 13.9°C hquid iodine monochloride has bromine-hke reddish-brown color hquid density 3.10 g/mL at 29°C viscosity 1.21 centipoise at 35°C decomposes around 100°C supercools below its melting point polar solvent as a hquid it dissolves iodine, ammonium chloride and alkali metal chlorides hquid ICl also miscible with carbon tetrachloride, acetic acid and bromine the solid crystals dissolve in ethanol, ether, acetic acid and carbon disulfide solid ICl also dissolves in cone. HCl but decomposes in water or dilute HCl. 

White crystalline deliquescent powder or granules saline and shght bitter taste absorbs moisture from air slowly turns brown on exposure to air due to iodine evolved density 3.67g/cm3 melts at 660°C vaporizes at 1,304°C vapor pressure 1 torr at 767°C and 5 torr at 857°C very soluble in water, 178.7 g/100 mL at 20°C and 294 g/100 ml at 70°C soluble in ethanol and acetone. 

Where y0 is the homogeneous dephasing at zero pressure, n is the number density, v is the average velocity, and s is the homogeneous dephasing cross section. A fit through the experimental data in Fig. 2 allows us to determine a cross-section of 1170 110 A2 for neat iodine vapor, and a 1 /yo of 58 4 ns. [ 1 ] This value is a factor of two larger than that determined two decades ago. [2]... 

In the time scale covered by the calculation, the 137I in the particles results from in situ decay of 137Te. The low surface concentration is associated with the high volatility of iodine in an oxidizing atmosphere. In this same figure the 137Xe curves reflect their parent 137I curves to some extent. The surface concentration of this element probably does not represent a true vapor pressure equilibrium but just the thermody-... 

I2 (g). Vapor pressure data on solid iodine were reported by Baxter and Grose,1 Baxter, Hickey, and Holmes,1 and Ramsay and Young.1 Haber and Kerschbaum1 measured the vapor pressure at low temperatures. Giauque2 critically reviewed the data, and deduced for the heat of sublimation, Fs= —16.069+0.0040 ( +273.1), which gives at 18°, —14.91. Earlier calculations were made by Wohl,3 Dewar,1 and Nernst.1... 

I2 (liq.). Vapor pressure data for liquid iodine were reported by Ramsay and Young,1 Stelzner and Niedersehulte,1 and Rassow.1 These data yield for the heat of vaporization, V— —12.75 + 0.0056 ( +273.1). Combination of this equation with that for the heat of sublimation gives for the heat of fusion of solid iodine, F= —3.3+0.0016 ( +273.1), or —4.0 at the melting point. See also Rideal.1... 

Only a few solids have vapor pressures near atmospheric at safe temperatures, among them COz, UF , ZrCL(, and about 30 organics. Ammonium chloride sublimes at 1 atm and 350°C with decomposition into NH3 and HC1, but these recombine into pure NH4C1 upon cooling. Iodine has a triple point 113.5°C and 90.5 Torr it can be sublimed out of aqueous salt solutions at atmospheric pressure because of the entraining effect of vaporized water. 

VOLATILE. Having a low boiling or subliming temperature at ordinary pressure in other words, having a high vapor pressure, as ether, camphor, naphthalene, iodine, chloroform, benzene or methyl chloride. 

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... 

Iodophors (tamed iodine) are compounds in which surface-active agents, such as nonoxynol, act as carriers and solubilizing agents for iodine. Iodophors usually enhance the bactericidal activity of iodine and reduce its vapor pressure and odor. Further, staining is avoided and high dilution with water is possible (130—132). 

Agl (g). Jellinek and Rudat2 computed the heat of vaporization from vapor pressure data. From the spectroscopic absorption limit and the assumption that the products of dissociation are a normal silver atom and an excited iodine atom, Franck and Kuhn1 computed a value for the energy of dissociation of gaseous silver iodide which leads to the value Qf= —38 for Agl (g). 

The emission from iodine vapor excited by monochromatic light may easily be photographed since it consists of a series of doublets. With addition of even a low pressure (e.g. 1 torr of helium) of foreign gas, the iodine molecules become distributed among so many rotational levels that the emission becomes very difficult to resolve even though a phototube may indicate virtually no decrease in total intensity. 

Solid iodine monochloride exists in two forms. The brownish-red tablets of the j8 form (m. 13.9°C.) are labile and pass readily into the ruby-red needles of the a form (m. 27.19°C.). Since iodine monochloride dissociates on boiling at atmospheric pressure, its boiling point is not definite. The literature gives values from 94.7° to 102°C. Calculations from vapor-pressure data give 33.4 cal. as the value of the entropy of vaporization at a vapor concentration of 0.00507 mol per liter. Iodine monochloride must therefore be an associated or polar liquid. 

Vapor pressure osmometric and spectroscopic studies on the molecular association and dissociation of (Z)-vinyl(bromo)-A3-iodane 130 in chloroform solution indicate the equilibrium formation of the dimer 131 as well as the iodonium ion 129, which is stabilized by the coordination of the solvent chloroform via the hypervalent interaction between the positively charged iodine and a chlorine atom [212]. 

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