Solids described

If you were given a sample of a white solid, describe some simple experiments that you would perform to help you decide whether or not the bonding involved primarily covalent bonds, ionic bonds, or van der Waals forces. 

Salt-inclusion solids described herein were synthesized at high temperature (>500°C) in the presence of reactive alkali and alkaline-earth metal halide salt media. For single crystal growth, an extra amount of molten salt is used, typically 3 5 times by weight of oxides. The reaction mixtures were placed in a carbon-coated silica ampoule, which was then sealed under vacuum. The reaction temperature was typically set at 100-150 °C above the melting point of employed salt. As shown in the schematic drawing in Fig. 16.2, the corresponding metal oxides were first dissolved conceivably via decomposition because of cor-... 

Zeolites form a class with tremendous variety. Besides the microporous solids described in the above, mesoporous materials have been synthesized. A breakthrough were the MCM-41 mesoporous zeolites with pores of typically 3 nm. Later, many related materials have been reported allowing fine-tuning of pore sizes. A recent example is the synthesis of materials with pores in the lOnm range with satisfactory uniformity and stability (Sun etai, 2001). 

The physical process of melt ascent during two-phase flow models is typically based on the separation of melt and solid described by Darcy s Law modified for a buoyancy driving force. The melt velocity depends on the permeability and pressure gradients but the actual microscopic distribution of the melt (on grain boundaries or in veins) is left unspecified. The creation of disequilibria only requires movement of the fluid relative to the solid. 

Using the pKa and the estimated So, the DTT procedure simulates the entire titration curve before the assay commences. Figure 6.7 shows such a titration curve of propoxyphene. The simulated curve serves as a template for the instrument to collect individual pH measurements in the course of the titration. The pH domain containing precipitation is apparent from the simulation (filled points in Fig. 6.7). Titration of the sample suspension is done in the direction of dissolution (high to low pH in Fig. 6.7), eventually well past the point of complete dissolution (pH <7.3 in Fig. 6.7). The rate of dissolution of the solid, described by the classical Noyes-Whitney expression [37], depends on a number of factors, which the instrument takes into account. For example, the instrument slows down the rate of pH data taking as the point of complete dissolution approaches, where the time needed to dissolve additional solid substantially increases (between pH 9 and 7.3 in Fig. 6.7). Only after the precipitate completely dissolves, does the instalment collect the remainder of the data rapidly (unfilled circles in Fig. 6.7). Typically, 3-10 h is required for the entire equilibrium solubility data taking. The more insoluble the... 

X-Ray Crystallographic Data for Solids Described as Colloidal Bismuth Subcitrate (Hcit = [C02CH2C(0H)(C02)CH2C02]3-)... 

A yellow solid described as decaphenylferrocene, [Fe(C5Ph5)2] (9) (Scheme 7), was originally reported as the product from the reaction of [Fe(CO)2Br(C5Ph5)] (10) with [Li(C5Ph5)] in refluxing xylene.56-57 Later... 

The value of (8bl + 6b2) thus calculated is 76867 x 10-12 ergs mol-1. The A /ss of solid solutions of CsCl and CsBr were evaluated (eqn. (1)) for different values of b2 (in the range 0-900 x 10-12 erg mol-1) using the r0 values from table 2. The results are shown diagramatically in fig. 3, the values of b, and b2 are 9257 x 10-12 and 468 x 10-12 erg mol-1 respectively when (6b2/%b1 + 6b2)csci (6b2l%bi + 6b2)csB,- The AUs s remains nearly constant with the % CsBr when b2 is between 400 and 500 x 10-12 erg mol-1. Thus, curves 3 and 4 of fig. 3 closely represent the experimentally observed situation. Thus, the Born model of ionic solids describes the relative stabilities of structures of alkali halides in widely different situations as manifested here by the CsCl+KCl and CsCl + CsBr systems. 

An aliquot of 30 pL is transferred in 250 pi buffer. The solution is shaken for 24 hours at 25 °C. If precipitation occurs the sample is centrifuged and filtrated. The following procedure is the same as for the solubility from solids described above. The achieved throughput is mainly limited by the gradient time. Pan et al. investigated the effect of filtration on the quantification of solubility. They recommend poly(tetrafluoroethylene) (PTFE) as filter material of choice. In their compound set they found 98% recovery after filtration. 

All the types of solids described previonsly can have fixed and volatile portions. The fixed portions of the solids are those that remain as a residue when the sample is decomposed at 600°C. Those that disappear are called volatile solids. Volatile solids and fixed solids are normally nsed as measures of the amount of organic matter and inorganic matter in a sample, respectively. Magnesinm carbonate, however, decomposes to magnesinm oxide and carbon dioxide at 350°C. Thns, the amount of organic matter may be overpredicted and the amount of inorganic may be underpredicted if the carbonate is present in an appreciable amount. 

Combined quantum mechanical/molecular mechanics calculations have become popular over the last decade or so in solid state modelling. Typically a molecule attaching to a surface or the side of a cage structure or an isolated defect is treated quantum mechanically as a cluster embedded in a bulk solid described by an interatomic potential method. One of the earliest examples of this approach was Vail s work on F-centres which began in 1983" " and which treated a cluster around the F-centre quantum-mechanically and the rest of the solid via an interatomic potential method. 

With strong bases such as HO and EtO", 1,2-dithiolium ions undergo extensive destruction, and these reactions are of little preparative value. Under milder conditions the dithiole ring may be preserved. For instance, 4-phenyl-l,2-dithiolium sulfate and aqueous sodium bicarbonate give a yellow crystalline solid described as bis(4-phenyl-3//-l,2-dithiol-3-yl) ether.This substance gives 4-phenyl-l,2-dithiolium perchlorate with perchloric acid. 

The chemical elements provide examples of three of the four classes of crystalline solids described in this section. Only ionic solids are excluded, because a single element cannot have the two types of atoms of different electronegativities needed to form an ionic material. We have already discussed some of the structures formed by metallic elements, which are sufficiently electropositive that their atoms readily give up electrons to form the electron sea of metallic bonding. The nonmetallic elements are more complex in their structures, reflecting a competition between intermolecular and intramolecular bonding and producing molecular or covalent solids with varied properties. 

The experiment described in Problem 1.59 is a crude but convenient way to determine the density of some solids. Describe a similar experiment that would allow you to measure the density of ice. Specifically, what would be the requirements for the liquid used in your experiment ... 

Explain why solids are essentially incompressible. Distinguish between amorphous and crystalline solids. Describe one property that is characteristic of ... 

List the properties of gases and compare gases, liquids, and solids Describe how pressure is measured... 

The noncrystalline solids described here are amorphous and metastable. This specific thermodynamic property is because they all originate from the liquid state. The corresponding glassy or vitreous materials are not very common in solid-state chemistry, and only a limited number of molten salts or molten alloys have the characteristics necessary to produce glasses when cooling. 

The ablation devices for solids described in Section 8C-2 are also available from several makers of ICP instruments, With these tvpes of sample-introduction systems, the plume of sapor and particulate matter produced by interaction of the sample with an electric arc or spark or with i laser beam are Iransporled h a tlow of argon into the torch where lurther alomizaiion and esciiaiion occur. 

The strength of a bound sand system is perhaps its most important property The effect of process variables on strength is shown in Figures 2-5. The term silicate solid describes the silicate content of the dehydrated sand specimen This term applies to that portion of the silicate binder that will not evaporate when heated above 105 0 Thus, the solvent water and... 

Structures The porous solids described in this chapter are periodically ordered materials. Nevertheless, a distinction can be made between the ordering of the atoms, as is observed in the case of crystaUine zeolites, for example, and long-range mesoscopic order associated with arrangements of pores, as observed for meso-porous materials such as MCM-41 or SBA-15 sUicas (see Section 9.5). In both cases. 

Define a crystalline solid. Describe in detail some important types of crystalline solids and name a substance that is an example of each type of solid. Explain how the particles are held together in each type of solid (the interparticle forces that exist). How do the interparticle forces in a solid influence the bulk physical properties of the solid ... 

Most of the molecular compounds with significant electrical conductivity or magnetic properties contain donor-acceptor pairs or are comprised of partially charged n-delocalized molecules. The two solids described in the previous section exemplify these two types. The generation of these properties in a single molecule, desir-... 

The Enthalpy of Solution simulation eChapter 13.1) deals specifically with dissolution of solids. Describe the solution process in terms of three distinct steps. Using the three steps, explain why gases, in contrast to most solids, become less soluble as temperature increases. 

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