Chemicals liquid/solid/volatile

Violent reaction between Al chlorinated hydrocarbons) 92)MCA General Safety Comm, "Guide for Safety in the Chemical Laboratory , Van Nostrand, NY (1954) 234 pp (Includes a tabulation of fire-hazard props of flammable liquids, gases volatile solids)... 

Solid phase micro-extraction (SPME) allows isolation and concentration of volatile components rapidly and easily without the use of a solvent. These techniques are independent of the form of the matrix liquids, solids and gases can be sampled quite readily. SPME is an equilibrium technique and accurate quantification requires that the extraction conditions be controlled carefully. Each chemical component will behave differently depending on its polarity, volatility, organic/water partition coefficient, volume of the sample and headspace, speed of agitation, pH of the solution and temperature of the sample (Harmon, 2002). The techniques involve the use of an inert fiber coated with an absorbant, which govern its properties. Volatile components are adsorbed onto a suitable SPME fiber (which are usually discriminative for a range of volatile components), desorbed in the injection chamber and separated by a suitable GC column. To use this method effectively, it is important to be familiar with the factors that influence recovery of the volatiles (Reineccius, 2002). 

The contaminant s aqueous solubility and density greatly influence its final disposition in water-solid systems. Dense nonaqueous phase liquids (DNAPLs) are chemicals with densities greater than water and typically low aqueous solubilities. DNAPLs naturally partition away from the aqueous phase and towards the solid phase, often pooling on top of an impermeable solid layer. On the other hand, light nonaqueous phase liquids (LNAPLs) possess densities less than water and have a tendency to pool on the water s surface where they may be prone to volatilization and photolysis reactions. Various liquid-solid partition coefficients have been... 

Foaming methods vary widely. One is to whip air into suspension or a solution of the plastic, which is then hardened by heat curing. A second is to dissolve a gas in a mix, then expand it when the pressure is reduced. Another is to heat a mixture until one of its liquid components volatilizes. Similarly, water produced in an exothermic chemical reaction can be volatilized within the mass by the heat of reaction. A different technique uses a chemical reaction to produce carbon dioxide gas within solid mass. A related way is for a gas such as nitrogen to be... 

If a gas phase is present, chemical species may volatilize from the liquid or solid phase, which is an important partitioning process in a variety of circumstances (e.g., transport in the unsaturated zone, or for treatment processes). The equilibrium vapor pressure can be used with the ideal gas law to estimate the mass in a given volume and temperature under equilibrium conditions. For solutions with more than one component, Raoult s law can be used to quantify the vapor pressure of each component. For dilute aqueous solutions, Henry s law describes the equilibrium relationship between dissolved chemicals and their vapor pressure ... 

Gas-to-liquid mass transfer is a transport phenomenon that involves the transfer of a component (or multiple components) between gas and liquid phases. Gas-liquid contactors, such as gas-liquid absorption/ stripping columns, gas-liquid-solid fluidized beds, airlift reactors, gas bubble reactors, and trickle-bed reactors (TBRs) are frequently encountered in chemical industry. Gas-to-liquid mass transfer is also applied in environmental control systems, e.g., aeration in wastewater treatment where oxygen is transferred from air to water, trickle-bed filters, and scrubbers for the removal of volatile organic compounds. In addition, gas-to-liquid mass transfer is an important factor in gas-liquid emulsion polymerization, and the rate of polymerization could, thus, be enhanced significantly by mechanical agitation. 

Solid-eatalyzed reactions can occur in either the liquid or gas phase. Gas-phase reactions are not very common in the production of fine chemieals, beeause eom-plex molecules with limited volatility and thermal stability are usually involved, which makes operation at the high temperatures required for their vaporization impossible. Gas-liquid reactions with a solid catalyst probably encompass the largest number of applications in fine-chemical and pharmaceutical processes [1]. Two other classes of solid-eatalyzed reaction taking place in the liquid phase are liquid-solid reactions and liquid-liquid-solid reactions, but these are much less eommon. We shall, therefore, foeus on gas-liquid-solid reaetions, in which the solid is a heterogeneous catalyst. 

VOC Volatile organic chemicals that are emitted from certain liquids and solids, volatilization The conversion of a solid or liquid to a gas or vapor by application of heat, by reducing pressure, by chemical reaction or by a combination of these processes. 

Gravimetric methods based on precipitation or volatilization reactions require that the analyte, or some other species in the sample, participate in a chemical reaction producing a change in physical state. For example, in direct precipitation gravimetry, a soluble analyte is converted to an insoluble form that precipitates from solution. In some situations, however, the analyte is already present in a form that may be readily separated from its liquid, gas, or solid matrix. When such a separation is possible, the analyte s mass can be directly determined with an appropriate balance. In this section the application of particulate gravimetry is briefly considered. 

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