Theory gases

Gases are compressible fluids. According to kinetic-molecular theory, gases are composed of molecules or single atoms that are in constant random motion throughout mostly empty space (unless the gas is highly compressed). A gas is easily compressed because the molecules can be pushed into a smaller space. A gas is fluid because individual molecules can move easily relative to one another. 

According to the kinetic theory, gases and hquids can be regarded as Newtonian particles having mass m, velocity v, and kinetic energy e, where... 

Matter, state of matter, kinetic molecular theory, gases, Uquids, solids... 

According to the kinetic molecular theory, gases are composed of particles with negligible volume that are separated by large distances the particles are in constant, random motion, and collisions between the particles and between the particles and their container walls are perfectly elastic there are no attractive or repulsive forces between the particles and the average kinetic energy of particles in a sample is proportional to the absolute temperature of the sample. 

The theories so far proposed for the flameproofing of cellulosic materials have been reviewed by Coppick(20). They may be broadly classified under four headings coating theories, gas theories, thermal theories, and chemical theories. 

Think about how the relationship between pressure and area for solids would apply if you were testing a gas in a three-dimensional container. You know that according to the kinetic molecular theory, gas molecules exert pressure over the entire inside surface of their container. If the volume of the container is halved, what would happen to the pressure of the gas inside the container ... 

According to the kinetic-molecular theory, gas particles that are at the same temperature have the same average kinetic energy. Therefore, the kinetic energy of two gases that are at the same temperature is... 

According to the kinetic molecular theory, gas pressure is the result of collisions between molecules and the walls of their container. It depends on the frequency of collision per unit area and on how hard the molecules strike the wall. The theory also provides a molecular interpretation of temperature. According to Equation (5.11), the absolute temperature of a gas is a measure of the average kinetic energy of the molecules. In other words, the absolute temperature is an index of the random motion of the molecules—the higher the temperature, the more energetic the molecules. Because it is related to the temperature of the gas sample, random molecular motion is sometimes referred to as thermal motion. 

Ans. According to the theory, gas molecules are in constant random motion, and change direction only upon collision with each other or the walls of their container. In their collisions with container walls, they exert a force on the wall. The total force of these wall collisions per unit time is the origin of gas pressure. 

Consecutive Mass Transfer and Reaction Simultaneous Mass Transfer and Reaction Instantaneous Reaction Penetration Theory Gas-Film Control... 

Key words electrode materials, electrode-oxide interfaces in gas sensors, physics of barrier formation, carrier transport theory, gas-solid... 

Gas-phase optimized geometries at the B97-1/MG3S level of theory. Gas-phase optimized geometries at the MPW25/M1DI level of theory. 

Scheme11.40 Summary of predicted geometric data of the transition structure calculated on various levels of theory (gas phase) [55].

According to kinetic theory, gas pressure is the result of the bombardment of the container walls by constantly moving molecules. 

According to kinetic theory, gas molecules are in constant random motion.When a molecule on the left side of the box happens to hit the pinhole in the partition between the two parts of the box, it passes (or effuses) to the right side.The rate of effusion depends on the speed of the molecules—the faster the molecules move,the more likely they are to encounter the pinhole and pass from the left side of the box to the right side. 

Gases do not have a definite shape or volume. They completely fill any container in which they are enclosed, and take its shape. A gas transferred from a one-liter vessel to a two-Uter vessel will expand to fiU the larger volume. The kinetic-molecular theory explains these facts. According to the theory, gas particles move rapidly in all directions (assumption 3), with no significant attraction between them (assumption 4). 

Two-Film Theory, Gas-Film Mass Transfer Coefficient, Liquid-Film Mass Transfer Coefficient, Overall Mass Transfer Coefficients,... 

The Maxwell relations are named for James Clerk Maxwell, 1831-1879, a great British physicist who made fundamental contributions to electromagnetic theory, gas kinetic theory, and thermodynamics. 

See also EPR Spectroscopy, Theory Gas Phase Applications of NMR Spectroscopy Microwave and Radiowave Spectroscopy, Applications Rotational Spectroscopy, Theory Solid State NMR, Rotational Resonance Vibrational, Rotational and Raman Spectroscopy, Historical Perspective. 

Langmuir adsorption isotherm A theoretical equation, derived from the kinetic theory of gases, which relates the amount of gas adsorbed at a plane solid surface to the pressure of gas in equilibrium with the surface. In the derivation it is assumed that the adsorption is restricted to a monolayer at the surface, which is considered to be energetically uniform. It is also assumed that there is no interaction between the adsorbed species. The equation shows that at a gas pressure, p, the fraction, 0, of the surface covered by the adsorbate is given by ... 

It must also be realized that this thin surface region is in a very turbulent state. Since the liquid is in equilibrium with its vapor, then, clearly, there is a two-way and balanced traffic of molecules hitting and condensing on the surface from the vapor phase and of molecules evaporating from the surface into the vapor phase. From the gas kinetic theory, the number of moles striking 1 cm of surface per second is... 

A related approach carries out lattice sums using a suitable interatomic potential, much as has been done for rare gas crystals [82]. One may also obtain the dispersion component to E by estimating the Hamaker constant A by means of the Lifshitz theory (Eq. VI-30), but again using lattice sums [83]. Thus for a FCC crystal the dispersion contributions are... 

The subject of gas adsorption is, indeed, a very broad one, and no attempt is made to give complete coverage to the voluminous literature on it. Instead, as in past chapters, the principal models or theories are taken up partly for their own sake and partly as a means of introducing characteristic data. 

In evaluating if a site can be regarded as a two-dimensional potential box, then the rate of adsorption will be given by the rate of molecules impinging on the site area oq- From gas kinetic theory. 

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... 

Mention was made in Section XVIII-2E of programmed desorption this technique gives specific information about both the adsorption and the desorption of specific molecular states, at least when applied to single-crystal surfaces. The kinetic theory involved is essentially that used in Section XVI-3A. It will be recalled that the adsorption rate was there taken to be simply the rate at which molecules from the gas phase would strike a site area times the fraction of unoccupied sites. If the adsorption is activated, the fraction of molecules hitting and sticking that can proceed to a chemisorbed state is given by exp(-E /RT). The adsorption rate constant of Eq. XVII-13 becomes... 

The Langmuir-Hinshelwood picture is essentially that of Fig. XVIII-14. If the process is unimolecular, the species meanders around on the surface until it receives the activation energy to go over to product(s), which then desorb. If the process is bimolecular, two species diffuse around until a reactive encounter occurs. The reaction will be diffusion controlled if it occurs on every encounter (see Ref. 211) the theory of surface diffusional encounters has been treated (see Ref. 212) the subject may also be approached by means of Monte Carlo/molecular dynamics techniques [213]. In the case of activated bimolecular reactions, however, there will in general be many encounters before the reactive one, and the rate law for the surface reaction is generally written by analogy to the mass action law for solutions. That is, for a bimolecular process, the rate is taken to be proportional to the product of the two surface concentrations. It is interesting, however, that essentially the same rate law is obtained if the adsorption is strictly localized and species react only if they happen to adsorb on adjacent sites (note Ref. 214). (The apparent rate law, that is, the rate law in terms of gas pressures, depends on the form of the adsorption isotherm, as discussed in the next section.)... 

Another important accomplislnnent of the free electron model concerns tire heat capacity of a metal. At low temperatures, the heat capacity of a metal goes linearly with the temperature and vanishes at absolute zero. This behaviour is in contrast with classical statistical mechanics. According to classical theories, the equipartition theory predicts that a free particle should have a heat capacity of where is the Boltzmann constant. An ideal gas has a heat capacity consistent with tliis value. The electrical conductivity of a metal suggests that the conduction electrons behave like free particles and might also have a heat capacity of 3/fg,... 

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