Characteristic gas constant

Here / is the universal gas constant (=8314 J/kgmol K), vv is the molecular weight of the fluid, R = R/w is the characteristic gas constant and Z is the compressibility factor, which will be a function of temperature in conditions of boiling or condensing. 

The inclusion of the characteristic gas constant, R, in this equation means that this equation can be used for any gas. Nitrogen, carbon dioxide, superheated steam and many other gases are often used for pneumatic conveying. The following equations, however, are derived in terms of air only. If any other gas is employed the equations will have to be re-worked with the appropriate value of R. 

The longest relaxation time. t,. corresponds to p = 1. The important characteristics of the polymer are its steady-state viscosity > at zero rate of shear, molecular weight A/, and its density p at temperature 7" R is the gas constant, and N is the number of statistical segments in the polymer chain. For vinyl polymers N contains about 10 to 20 monomer units. This equation holds only for the longer relaxation times (i.e., in the terminal zone). In this region the stress-relaxation curve is now given by a sum of exponential terms just as in equation (10), but the number of terms in the sum and the relationship between the T S of each term is specified completely. Thus... 

In these formulas the letter X stands for the average copolymer composition, while of denotes the dispersion of the SCD quantitatively characterizing its width. The second of these statistical characteristics is extremely significant for the thermodynamics of the melt of a heteropolymer specimen, being in a simple way AHmix = RT jof connected with the specific enthalpy of mixing Affmix per mole of monomeric units. Here T is the absolute temperature, R represents the gas constant, whereas / denotes the Flory /-parameter whose values are available from the literature for many pairs of monomeric units (see, for example, [7]). 

Figure 24. Models illustrating the source of chemical capacitance for thin film mixed conducting electrodes, (a) Oxygen reduction/oxidation is limited by absorption/de-sorption at the gas-exposed surface, (b) Oxygen reduction/ oxidation is limited by ambipolar diffusion of 0 through the mixed conducting film. The characteristic time constant for these two physical situations is different (as shown) but involves the same chemical capacitance Cl, as explained in the text.

Cantor and SchimmeP provide a lucid description of the thermodynamics of the hydrophobic effect, and they stress the importance of considering both the unitary and cratic contributions to the partial molal entropy of solute-solvent interactions. Briefly, the partial molal entropy (5a) is the sum of the unitary contribution (5a ) which takes into account the characteristics of solute A and its interactions with water) and the cratic term (-R In Ca, where R is the universal gas constant and ( a is the mole fraction of component A) which is a statistical term resulting from the mixing of component A with solvent molecules. The unitary change in entropy 5a ... 

Unlike the relation between brisance and PCJ, expl strength is not readily related to some detonation characteristic of the explosive. Attempts to relate strength to detonation energy are not wholly successful. Relative strength, based on ballistic mortar tests, correlates rather well with computed nRT, where n T are the computed moles of gas and detonation temp of the explosive, and R is the gas constant. Although n T can differ appreciably with the equation of state used in the computation, it appears that ratios of nRT (at least for similar explosives) do not suffer from this drawback... 

We know from theoretical principles, however, (and your text may explain this) that the vapor pressure of a liquid is related to its heat of vaporization (AHv), which is a physical constant characteristic of the liquid, to the gas constant (R = 1.987 cai/mole deg), and to the Kelvin temperature (T), by the equation... 

The constant b is regarded as the correction to the molar volume due to the volume occupied by the molecules. Constants a and b are characteristic of the particular gas, whereas R is the universal gas constant. 

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