Vapor pressure, solids

The drying mechanisms of desiccants may be classified as foUows Class 1 chemical reaction, which forms either a new compound or a hydrate Class 2 physical absorption with constant relative humidity or vapor pressure (solid + water + saturated solution) Class 3 physical absorption with variable relative humidity or vapor pressure (soHd or liquid + water + diluted solution) and Class 4 physical adsorption. 

Almost all the materials which are being considered as components in automobile exhaust catalyst are somewhat toxic (74)- Most of the compounds considered are low vapor pressure solids which can only escape from the exhaust system as very fine airbone dust particles formed by catalyst attrition. A few compounds, such as the highly toxic metal carbonyls and ruthenium tetroxides, are liquid under ambient conditions and have boiling points less than 100 °C. These compounds are not present in... 

How are low vapor pressure solid samples introduced into the source of a mass spectrometer (direct insertion probe). 

Liquids, vapor pressure, solids, phase changes 5.8-5.11... 

The metalorganic precursor compounds that have been most commonly used to grow thin films of semiconductors and related materials are listed below in Table I, along with the currently available vapor pressure data. These precursors are typically pyrophoric liquids or high-vapor-pressure solids. The simple metal alkyls (methyl and ethyl derivatives) are the most often employed for the growth of III-V compound semiconductors since they have reasonably high vapor pressures and can be readily delivered using a H2 carrier gas and precursor source temperatures conveniently near room temperature. 

C. Only temperature and the identity of the substance determine vapor pressure. Solids have a vapor pressure, and solutes decrease vapor pressure. 

A thermal rocket of recent development which produces low thrust and specific impulse for satellite control purposes is the subliming propellant rocket. In this rocket the propellant is ordinarily a high vapor pressure solid. Propellant flow rate is controlled by the addition of heat to the subliming propellant. Desirable properties of propellants for such rockets is stability in the solid phase, high vapor pressure, and, as for all thermal rocket propellants, low molecular weight of the vapor produced. 

Compoimd Ambient state" Oxygen sensitivity Vapor pressure Solid Vapor... 

Figure 3 log/o -pH diagram for the solubility of gold as Au(HS)2, at 200 °C and saturated water vapor pressure. Solid lines delineate mineral-stability fields dotted lines delineate the fields of dominance for dissolved sulfur species (total dissolved sulfur = 0.01 m), and dashed lines show gold solubility contours. Drawn for an activity of water equal to unity (after Wood and Samson, 1998). 

The solvent precipitation method utilizes the unique properties of nonsolvent at a critical temperature and pressure to precipitate solid particles of drugs from solutions. Carbon dioxide, which exhibits remarkable solvent power at its critical temperature of 31.1°C and pressure of 70 bar for high molecular weight and low vapor pressure solids, is an ideal nonsolvent choice. CO2 is also nontoxic, inexpensive, and readily available. The technology has been successfully applied to the production of fine particles for aerosol delivery. ... 

Some solids, such as iodine and carbon dioxide, vaporize at atmospheric pressure without passing through the liquid state. This process is known as sublimation. Solids exhibit vapor pressures just as liquids do, but they generally have much lower vapor pressures. Solids with high vapor pressures sublime easily. The characteristic odor of a common household solid, j) r -dichlorobenzene (moth repellent), is due to sublimation. The reverse process, by which a vapor solidifies without passing through the liquid phase, is called deposition. 

Cagniard de la Tour discovered the critical point in 1822. Hannay and Hogarth reported on the ability of a supercritical fluid to dissolve low vapor pressure solid materials (1). Since then, a spectrum of solids have been studied in a variety of supercritical fluids. Naphthalene is the most extensively studied solute, and carbon dioxide the most popular supercritical fluid. Over the last decade, a large number of books have been published on SFE (2-17). Most of these are proceedings of conferences. McHugh and Krukonis present a good historical review of the research and process applications in this field (8). Bruno and Ely review the theory and practical applications of SFE (3). 

Samples can be introduced into the lAMS systems by several different methods, such as a leak for samples in a gas/hquid inlet, from a DIP for solids, and by online combinations with chromatography (see 6.1, application to GC-MS mode). A controlled leak is a simple method, but its use is restricted to samples with high vapor pressure. Solid and liquid samples can be introduced with a heated DIP (or an insertion probe). Either gas chromatography or liquid column chromatography can... 

X Kci = 100 Wkci/(Wkci + WNaci), where Wkci and WNaci are the weight amounts of KCl and NaCl in aqueous solution (solvent-free concentration) temperature near isotherms (a) shown in °C pressure near isobars (b) shown in MPa. Heavy lines are the composition of eutonic solutions saturated with two solid phases at vapor pressure solid lines show (a) the isothermal composition of solid saturated liquid solutions at vapor pressure and (b) the composition of solid saturated liquid solution at constant vapor pressure. 

RC Petersen, DW Matson, RD Smith. Rapid precipitation of low vapor pressure solids from supercritical fluid solutions the formation of thin films and powders. J Am Chem Soc 108 2102-2103, 1986. 

Operating condition and physical properties, such as pressure, temperature, density, viscosity, vapor pressure, % solid content... 

There are several low vapor pressure solid (dry) lubricant and antistick (antiseize) compound materials that are vacuum-compatible. These include the sulfides (M0S2 and WS2 lubricants, usable to 10 Torr), silicides (WSi2 - antistick), and selenides (WS 2 - electrical conductors). Care should be taken to ensure that any binder materials used in the materials are also vacuum-compatible. Sputter-deposited M0S2 and M0S2 + Ni lubricants, in particular, have been shown to be acceptable in vacuums and are used by NASA for space applications. 

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