Cal

The values of common hydrocarbon solubility parameters vary between 300 and 600 (kJ/m3) /2 Several tables are available where the solubility parameters are shown as (cal/cm ) / Jq convert these values, it is necessary to multiply by 64.69. Thus a solubility parameter value of 10 (cal/cm ) / jg equal to 646.9 (kJ/m ) / ... 

Zero setup segment Sect.l ( 0% LMA ) cal.standard N2 Flaw setup segment Sect.2 ( 12.4% LMA ) cal.standard N2 LF calibration... 

The excess heat of solution of sample A of finely divided sodium chloride is 18 cal/g, and that of sample B is 12 cal/g. The area is estimated by making a microscopic count of the number of particles in a known weight of sample, and it is found that sample A contains 22 times more particles per gram than does sample B. Are the specific surface energies the same for the two samples If not, calculate their ratio. 

As a quite different and more fundamental approach, the isotherms of Fig. XI-10 allowed a calculation of X as a function of temperature. The plot of In K versus 1 /T gave an enthalpy quantity that should be just the difference between the heats of immersion of the Graphon in benzene and in n-heptane, or 2.6 x 10 cal/m [141]. The experimental heat of immersion difference is 2.4 x 10 cal/m, or probably indistinguishable. The... 

The example of Section XI-5B may be completed as follows. It is found that 0 = 0.5 at a butanol concentration of 0.3 g/100 cm. The heat of solution of butanol is 25 cal/g. The molecular area of adsorbed butanol is 40 A. Show that the heat of adsorption of butanol at this concentration is about 50 ergs/cm. ... 

Molecular moments of inertia are about 10 g/cm thus 7 values for benzene, N2, and NH3 are 18, 1.4, and 0.28, respectively, in those units. For the case of benzene gas, a = 6 and n = 3, and 5rot is about 21 cal K mol at 25°C. On adsorption, all of this entropy would be lost if the benzene were unable to rotate, and part of it if, say, rotation about only one axis were possible (as might be the situation if the benzene was subject only to the constraint of lying flat... 

The contact angle for water on single-crystal naphthalene is 87.7° at 35°C, and ddjdT is -0.13 deg/K. Using data from Table III-l as necessary, calculate the heat of immersion of naphthalene in water in cal/g if a sample of powdered naphthalene of 10 m /g is used for the immersion study. (Note Ref. 135.)... 

Bartell and Flu [19] were able to determine the adhesion tension, that is, ysv -7SL. for the water-silica interface to be 82.8 ergs/cm at 20°C and its temperature change to be -0.173 erg cm K . The heat of immersion of the silica sample in water was 15.9 cal/g. Calculate the surface area of the sample in square centimeters per gram. 

Harkins and Jura [21] found that a sample of Ti02 having a thick adsorbed layer of water on it gave a heat of inunersion in water of 0.600 cal/g. Calculate the specific surface area of the Ti02 in square centimeters per gram. 

The acconunodation coefficient for Kr on a carbon filament is determined experimentally as follows. The electrically heated filament at temperature 72 is stretched down the center of a cylindrical cell containing Kr gas at 7. Gas molecules hitting the filament cool it, and to maintain its temperature a resistance heating of Q cal sec cm is needed. Derive from simple gas kinetic theory the expression... 

F. Gordon, W. P. Gomes, and W. Dekeyser, eds., Photovoltaics and Photoelectrochemi-cal Solar Energy Conversion, Plenum, New York, 1981. 

DETHERM Dechema e.V, FIZ Chemie Berlin GmbH diermophysi-cal properties nu- meric, factual, biblio. 442000 records, 57000 biblio. journals, patent offices, proceedings, books STN in-house, online twice a year wuw.dechem- a.de... 

A series of topolo cal indices have been devised during the period since the 1950s. These are numbers derived from the cormectivity of a given structure. 

HyperClicm cati plot orbital wave fuuctious resulting fmni serni-cmpirical and ah i/iitw quan tii m m ecli an ica I calculations. It is ill tercstiu g to view both tli c u tidal properties an d th e relative sizes of the wave functions. Orbital wave functiou s can provide dietni-cal in sigh is. 

In the first time step (At), the velocities advance from time t=() to (t +1/2 At). In doing so, they Meap" over the positions at time t. The current velocities are then calculated using etiiiation 27. Th IS equation supplies on ly approximate velocities used to cal-cii late energies at time t. 

Convergence limit and Iteration limit specify th e precision of the cal-ciilation. Convergence limit refers to the dilTereiice in energy (in kcal/mol) between two successive SCE cycles. Iteration limit specifies the maximum number of cycles allowed to reach that goal. 

Note You cannot use the Hxicndcd Hiickel method or any one of th e-SCH m eth ods with theCI option being turn ed on forgeometry optim i/.ation s, m olecular dynam ics sim ulation s or vibrational cal-culations, in the ctirrcrit version ofHypcrChem. 

You can use any ah initio SCT calciilalion and all Ihe semi-empiri-cal methods, except Extended Hiickel. for molecular dynamics simulations. The procedures and considerations are similar for sim u lation s using molecular mech anics m eihods (see Molecular Dynamics" on page 69). 

For example, semi-empirical calculation s on a substrate m oleculc provide a set o f ch arges th at you can use in a m olecu lar m ech an ics calculation of the interaction of that substrate with another molecule. Fo include the effects of po lari,ration, repeated sem i-empiri-cal calculations can provide a set of charges that respond to the en viron rn en t. 

A back end program essentially acts as a computational server for the front end. It receivcsinpiit, computes something, sendsit back to the front end and then looks for further input or commands from the front end. It can be used over and over for different cal-cii lation s. If it has been explicitly stopped, the Iron t end will start... 

For a molecular mechanics calculation the en ergy and the gradient are essen tially the on ly quantities available from a single pom t cal-cii lation. An analysis of the com ponen ts of th is molecular mechanics energy is placed in the log file for further detail. In the case of MM-h a much more com pleie description of the ind ividual... 

HyperChern docs not nse con strained oplirn izatiori bnt it is possible Lo restrain m olecular in ech an ics and i]tiarituin median ics cal-cti latiori s hy adding extra restraining forces. 

Iditional importance is that the vibrational modes are dependent upon the reciprocal e vector k. As with calculations of the electronic structure of periodic lattices these cal-ions are usually performed by selecting a suitable set of points from within the Brillouin. For periodic solids it is necessary to take this periodicity into account the effect on the id-derivative matrix is that each element x] needs to be multiplied by the phase factor k-r y). A phonon dispersion curve indicates how the phonon frequencies vary over tlie luin zone, an example being shown in Figure 5.37. The phonon density of states is ariation in the number of frequencies as a function of frequency. A purely transverse ition is one where the displacement of the atoms is perpendicular to the direction of on of the wave in a pmely longitudinal vibration tlie atomic displacements are in the ition of the wave motion. Such motions can be observed in simple systems (e.g. those contain just one or two atoms per unit cell) but for general three-dimensional lattices of the vibrations are a mixture of transverse and longitudinal motions, the exceptions... 

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