Of gases at various temperatures

The Density of a Perfect Gas. Since density is defined as the weiglit per unit volume, the general gas law can be used to calculate densities of gases at various temperatures and pressures. Solving the general gas law for Wt/Y... 

Values of // — H%, known as the relatiTe heat content, for a number of gases at various temperatures, calculated from partition functions by means of equation (33.47), have been recorded (Table XXVI). For pure solids. 

Of a special astronomical interest is the absorption due to pairs of H2 molecules which is an important opacity source in the atmospheres of various types of cool stars, such as late stars, low-mass stars, brown dwarfs, certain white dwarfs, population III stars, etc., and in the atmospheres of the outer planets. In short absorption of infrared or visible radiation by molecular complexes is important in dense, essentially neutral atmospheres composed of non-polar gases such as hydrogen. For a treatment of such atmospheres, the absorption of pairs like H-He, H2-He, H2-H2, etc., must be known. Furthermore, it has been pointed out that for technical applications, for example in gas-core nuclear rockets, a knowledge of induced spectra is required for estimates of heat transfer [307, 308]. The transport properties of gases at high temperatures depend on collisional induction. Collision-induced absorption may be an important loss mechanism in gas lasers. Non-linear interactions of a supermolecular nature become important at high laser powers, especially at high gas densities. 

A particular example of the application in equation (2.8) is the Knudsen effect for the stationary state of the vessels with the same rarefied ideal gases at various temperatures and a small hole between the vessels. The small... 

The application of this result to the measurement of the degree of dissociation of gases at high temperatures was suggested by Weide and Bichowsky 9 xhe method is to allow a small constant flow of gas at a constant low pressure to escape through a small hole. If the gas dissociates near the hole according to the equation A2 2A the various molecular species will escape at a rate which... 

The heat capacity of all substances increases with increasing temperature. Table 8.1 lists the molar heat capacities of several common gases at various temperatures. 

Further studies on the decomposition of starch at various temperatures were conducted by Picon. He characterized the composition of gases evolved from pea, wheat, rice, and potato starch, as well as potato amylopec-tin and soluble starch from potatoes, when heated at temperatures fix)m 300 to 1000° (see Table XXIII). It may be seen that there are quite remarkable differences in the pyrolysis of various starches. However, these differences cannot be ascribed solely to the kind, but also to the variety, of plant that produced the starch. The thermal properties of the starch from two different varieties of a given plant differ more than those of starches from two kinds of starch (see Table XXIV). ... 

Among other zeolitic phases 6—(Ni11 r Col , )-(4-methylpyridine)4 (SCN)2 sorbs both non-polar and polar species (permanent and inert gases alkyl halides n-, iso- and cycloparaffins and aromatic hydrocarbons alcohols and ethers). The host lattice can scmetimes change at critical loadings of sorbate from one porous structure to another. This causes the steps seen in Fig. 2 for sorption isotherms of Xe at various temperatures [15]. 

THERMAL CONDUCTIVITY OF PURE GASES AT VARIOUS TEMPERATURES AND PRESSURES. 

NEWLY MEASURED VALUES OF THE HEAT CONDUCTIVITY AND SPECIFIC HEAT OF SEVERAL GASES AT VARIOUS TEMPERATURES. 

Decomposition of poly(ethylene terephthalate) as recorded using TG-DTA-FTIR. (A) Simultaneous TG-DTA curves. (B) IR absorption spectra of the evolved gases at various temperatures. (C) Specific gas profiles of the evolved gases. 

This book is a critical compilation of the virial coefficients of about 300 gases at various temperatures. Included are references to the original sources as well as, in some cases, standard deviations and estimated inaccuracies for the data. This revised edition also includes data on gaseous mixtures. 

The conversion (%) of CO and the molar fraction (%) of CH4 (mol%) in the tail gases at various temperatures (205, 260, 305, 350 395 and 440 °C) are shown in the figure. The order of the activity and selectivity for the above three methanation catalysts is Ni-La203-Pd/Al203 Ni-La203/ Al203>NAl203. 

In [20] the kinetics of the thermal decomposition of polyhexamethyl-eneadipamide was studied. The curves in Fig. 107 show the loss in weight as a function of the time of heating at various temperatures (within the interval 280-400°C). At 280-305°C, the loss in weight is 10-20% after 16 hr at 400°C, 85% of the initial sample is already liberated in the form of volatile products after 2 hr. Ammonia has been detected among the gaseous products, together with carbon dioxide. The kinetic curves of the formation of these gases, cited in Fig. 108, exhibit an induction period. 

Fig. 13.8 Polarization curves under hydrogen and oxygen gases at various temperatures of PA-doped 2,5-py-PBI membranes [30]...

One of the first quantitative observations of gases at different temperatures was made by Jacques Alexandre Charles in 1787. Charles was a French physicist and a pioneer in hot-air and hydrogen-filled balloons. Later, John Dalton (in 1801) and Joseph Louis Gay-Lussac (in 1802) continued these kinds of experiments, which showed that a sample of gas at a fixed pressure increases in volume linearly with temperature. By linearly, we mean that if we plot the volume occupied by a given sample of gas at various temperatures, we get a straight line (Figure 5.9). 

A successful practical embodiment of the method was achieved by Patat and Schmid [20] (Fig. n.3). The particles fall on the horizontal test plate 4, on rotating of which they slide and are collected in the collector 6, which has 12 sockets, so that 12 measurements may be made in one experiment. A potential of up to 1.5 kV may be applied to the plate. The body of the apparatus is airtight, so that experiments may be made in vacuum or in various vapors and gases at various temperatures. 

Rotary kilns operate at various temperatures throughout their length. A graph of approximate gas and charge temperatures for wet-process cement is shown in Fig. 12-67. The maximum charge temperature is 1700 to 1800 K for the gases, 1800 to 1925 K. Overall heat-transfer rates have been estimated to be in the range of 25 to 60 KJ/(s-m ) on the basis of total kiln volume. 

Table 21.22 Saturated solubilities of atmospheric gases in sea-water at various temperatures Concentrations of oxygen, nitrogen and carbon dioxide in equilibrium with 1 atm (lOI 325 N m ) of designated gas...

The average Nusselt number is not very sensitive to changes in gas velocity and Reynolds number, certainly no more than (Re)I/3. The Sherwood number can be calculated with the same formula as the Nusselt number, with the substitution of the Schmidt number for the Prandtl number. While the Prandtl number of nearly all gases at all temperatures is 0.7 the Schmidt number for various molecules in air does depend on temperature and molecular type, having the value of 0.23 for H2, 0.81 for CO, and 1.60 for benzene. 

Gas-liquid relationships, in the geochemical sense, should be considered liquid-solid-gas interactions in the subsurface. The subsurface gas phase is composed of a mixture of gases with various properties, usually found in the free pore spaces of the solid phase. Processes involved in the gas-liquid and gas-solid interface interactions are controlled by factors such as vapor pressure-volatilization, adsorption, solubility, pressure, and temperature. The solubility of a pure gas in a closed system containing water reaches an equilibrium concentration at a constant pressure and temperature. A gas-liquid equilibrium may be described by a partition coefficient, relative volatilization and Henry s law. 

Caicuiations performed by Woian et ai. of the caicuiated vaiues of vapor pressure of SiC for temperatures of interest for impiant anneaiing have been reported in the iiterature and the reader is referred to these caicuiations for compieteness [85]. From these caicuiations it was determined that the required vapor pressure of SiC at iower temperatures (< 1,600°C) is very smaii, as expected. The reiationship between vapor pressure, Vj, and temperature, T, is exponentiai. Fience an exponentiai curve fit was appiied for vapor pressure caicuiations for temperatures iess than 2,500°C. To optimize the process, the siiane fiow rates were caicuiated for various anneaiing temperatures and process pressures. The partiai pressure of siiane and the vapor pressure of SiC obtained in Section 4.3.2 under atmospheric pressure (AP) conditions are used here as the reference vaiues. Aii of the caicuiations were performed based on initiai anneaiing experiments conducted at 1,600°C with siiane (20 seem) and argon (6 sim) as the process gases. (These experimentai conditions wiii be discussed next.)... 

Clearly, 254 K is much colder than the typical temperatures around 288 K (15°C) found at the earth s surface. This difference between the calculated effective temperature and the true surface temperature is dramatically illustrated in Fig. 14.4, which shows the spectra of infrared radiation from earth measured from the Nimbus 4 satellite in three different locations, North Africa, Greenland, and Antarctica (Hanel et al., 1972). Also shown by the dotted lines are the calculated emissions from blackbodies at various temperatures. Over North Africa (Fig. 14.3a), in the window between 850 and 950 cm-1, where C02, O-, HzO, and other gases are not absorbing significantly, the temperature corresponds to blackbody emission at 320 K due to the infrared emissions from hot soil and vegetation. 

---