SELECT PROPERTIES OF LIQUIDS

Cation Anion Melting Point ( C) Decomposition Temperature (°C) 

Common anions found in ionic liquids include the PFg , BF4, and haUde ions. 

Ionic liquids have many useful properties. Unlike most molecular liquids, they are nonvolatile (that is, they don t evaporate readily) and nonflammable. They tend to remain in the liquid state at temperatures up to about 400 °C. Most molecular substances are liquids only at much lower temperatures, 100 °C or less in most cases (see Table 11.3). Because ionic liquids are good solvents for a wide range of substances, ionic liquids can be used for a variety of reactions and separations. These properties make them attractive replacements for volatile organic solvents in many industrial processes. Relative to traditional organic solvents, ionic liquids offer the promise of reduced volumes, safer handling, and easier reuse, thereby reducing the environmental impact of industrial chemical processes. 

The intermolecular attractions we have just discussed can help us understand many familiar properties of liquids. In this section we examine three viscosity, surface tension, and capillary action. 

Viscosity is related to the ease with which the molecules of the liquid can move relative to one another. It depends on the attractive forces between molecules and on whether the shapes and flexibility of the molecules are such that they tend to become entangled (for example, long molecules can become tangled like spaghetti). For a series of related compounds, viscosity increases with molecular weight, as illustrated in T Table 11.5. The SI unit for viscosity is kg/m-s. 

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Selected Properties of Liquids Used for Cooling Micro-Devices... 

SELECT PROPERTIES OF LIQUIDS We learn that the nature and strength of the intermolecular forces between molecules are largely responsible for many properties of liquids, including viscosity and surface tension. 

SELECT PROPERTIES OF LIQUIDS (SECTION 11.3) The stronger the intermoiecuiar forces, the greater is the viscosity, or resistance to flow, of a liquid. The surface tension of a liquid also increases as intermoiecuiar forces increase in strength. Surface tension is a measure of the tendency of a liquid to maintain a minimum smface area. The adhesion of a liquid to the walls of a narrow tube and the cohesion of the liquid account for capillary action. 

For the non-oxidative activation of light alkanes, the direct alkylation of toluene with ethane was chosen as an industrially relevant model reaction. The catalytic performance of ZSM-5 zeolites, which are good catalysts for this model reaction, was compared to the one of zeolite MCM-22, which is used in industry for the alkylation of aromatics with alkenes in the liquid phase. The catalytic experiments were carried out in a fixed-bed reactor and in a batch reactor. The results show that the shape-selective properties of zeolite ZSM-5 are more appropriate to favor the dehydroalkylation reaction, whereas on zeolite MCM-22 with its large cavities in the pore system and half-cavities on the external surface the thermodynamically favored side reaction with its large transition state, the disproportionation of toluene, prevails. 

Selected Properties of the Motor Gasoline and Diesel Fuel Refined from Fe-HTFT Syncrude and Coal Liquids at Sasol 2, Which Were Marketed as Final Products in South Africa in the 1980s... 

Weber, Handbook of Selected Properties of Air- and Water-Reactive Materials , RDTR No 144, NAVAMDEP, Crane (1969), 25-26 18) R.Kh. Kurbangalina, Dependence of Critical Diameter of Liquid Explosives on Content of Powders , LA-TR-20-8, translated by H. Dahlby from ZhPriklMekhTekhFiz (4), 133-36 (1969) CA 71,126697 (1969) 19) A.S. Derzhavets,... 

The huge versatility of the molecular structures combined with the unique properties makes liquid crystalline crowns interesting compounds for future research. Combination of selective ion complexation, ion conductivity, or even electric conductivity within the substituents gives rise to materials for use in biological or electronic devices. However, much has to be done to develop such systems and to understand fully the properties of liquid crystalline crowns. 

TABLE I Selected Properties of Cryogenic Liquids at Normal Boiling Point... 

In gas chromatography, the selective properties of these substances are used in GSC or GLC, where the substances act as a selective component of the stationary liquid phase (4). 

Fast separations of 16 PAHs were achieved within 6-7 min using packed columns. A comparison study of the PAH molecular shape recognition properties of liquid-crystal-bonded phases in packed-column SFC and HPLC found that the selectivity was enhanced in SFC. The result of an interlaborotory round-robin evaluation of SFC for the determination of PAHs also shows that SFC possesses distinct advantages over GC-mass spectrometry (MS) and nuclear magnetic resonance (NMR) including speed, cost, and applicability. 

Selected thermodynamic properties of liquid COFj have been estimated [1683]. These calculated values for the Helmholtz free energy function (-G/RT), liquid entropy (5), and heat capacity at constant volume (C,) are recorded in Table 13.11. 

Selected mechanical properties of liquid COFj have been estimated from molecular data [1683]. The calculated values for the molar volume, thermal expansion coefficient (a), and isothermal compressibility (3), are recorded as a function of temperature in Table 13.16. 

Bioselective electrodes are a class of hybrid devices which combine the selective properties of biocatalytic reactions with ISE detection of liberated ions or gases. In contrast to the organic ion liquid membrane electrodes described above, the bioelectrodes can often possess extraordinary selectivity over molecules which are very similar in structure to the analyte. In addition, these devices can respond to nonionic species. Consequently, such electrodes can be used directly in biological samples to determine a wide variety of biochemicals accurately. 

Selected properties of NH3 are listed in Table 8.4 and are compared with those of water it has a liquid range of... 

An alternative to molecular dynamics based simulated annealing is provided by Metropolis importance sampling Monte Carlo (Metropolis et al., 1953) which has been widely exploited in the evaluation of configurational integrals (Ciccotti et al., 1987) and in simulations of the physical properties of liquids and solids (Allen and Tildesley, 1987). Here, as outlined in Chapters 1 and 2, a particle or variable is selected at random and displaced both the direction and magnitude of the applied displacement within standard bounds are randomly selected. The energy of this new state, new, is evaluated and the state accepted if it satisfies either of the following criteria ... 

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