Mass of gas

Boyle s law At constant temperature the volume of a given mass of gas is inversely proportional to the pressure. Although exact at low pressures, the law is not accurately obeyed at high pressures because of the finite size of molecules and the existence of intermolecular forces. See van der Waals equation. 

Charles s law At constant pressure the volume of a given mass of gas is directly proportional to the absolute temperature. 

Henry s law The mass of gas which is dissolved by a given volume of a liquid at constant temperature is directly proportional to the pressure of the gas. The law is only obeyed provided there is no chemical reaction between the gas and the liquid. 

The heats of combustion of methane and butane are 890 kj/mol (212 8 kcal/mol) and 2876 kJ/mol (687 4 kcal/mol) respectively When used as a fuel would methane or butane generate more heat for the same mass of gas" Which would generate more heat for the same volume of gas" ... 

The quantity of gas adsorbed may of course be expressed in other ways, notably as the mass of gas (usually mg) or the volume of gas reduced to stp (usually cm (stp)). Unless immediate convenience dictates otherwise, however, the use of moles (or in some contexts, molecules) is to be preferred. In particular the common but loose expression volume of gas adsorbed at pressure p is highly ambiguous. 

The two major difficulties facing the analyst/mass spectrometrist concern firstly how to get the whole of the sample into the plasma flame efficiently and secondly how to do so without destabilizing or extinguishing the flame. Although plasma flames operate at temperatures of 6000 to 8000 K, the mass of gas in the flame is very small, and its thermal capacity is correspondingly small (Figure 15.1). 

Several additional terms related to the absorption of x-radiation require definition energy of a x-ray photon is properly represented in joules but more conveniently reported in eV fluence is the sum of the energy in a unit area intensity or flux is the fluence per unit time and the exposure is a measure of the number of ions produced in a mass of gas. The unit of exposure in medicine is the Rn ntgen, R, defined as the quantity of radiation required to produce 2.58 x C/kg of air. The absorbed dose for a tissue is a measure of energy dissipated per unit mass. The measure of absorbed dose most... 

Tti e wet-bulb temperature is established by a dynamic equilibrium between heat and mass transfer when liquid evaporates from a small mass, such as the wet bulb of a thermometer, into a veiy large mass of gas such that the latter undergoes no temperature or humidity change. It is expressed by the relationship... 

According to Ktiudsen if a small circular orifice of diameter less than the mean free path of the molecules in a container, is opened in the wall of the container to make a connection to a high vacuum sunounding the container, the mass of gas effusing tlnough the orifice, of area A, is given by an equation derived from the kinetic theoty, where tire pressure is in amiospheres. 

The interaction between radiation and a mass of gas can be treated as a collision problem. In this case the number of photon-molecule collisions, Nx, in unit length of an absorbing gas is given by... 

The conecting term in the pressure reflects the diminution in tire impact velocity of atoms at the containing walls of tire gas due to the attraction of the internal mass of gas, and the volume term reflects the finite volume of the molecules. Data for these two constants are shown in Table 3.4. 

Equations (12.40) to (12.45) describe the velocities u, v, w, the temperature distribution T, the concentration distribution c (mass of gas per unit ma.ss of mixture, particles per volume, droplet number density, etc.) and pressure distribution p. These variables can also be used for the calculation of air volume flow, convective air movement, and contaminant transport. 

A differential volume element dV in the flow field contains a mass of gas dm and a mass of solids dni. The corresponding volumes taken by gas and solids are denoted by tiV and dY. The sum of these partial volumes is the total volume of the mixture. 

Tlie two precursors of tlie ideal gas law were Boyle s low and Charles law. Boyle found tliat tlie volume of a given mass of gas is inversely proportional to die absolute pressure if die temperature is kept constant, tliat is,... 

M. Amon and C. D. Denson [33-34] attempted a theoretical and experimental examination of molding a thin plate from foamed thermoplastic. In the first part of the series [33] the authors examined bubble growth, and in the second [34] — used the obtained data to describe how the thin plate could be molded with reference to the complex situation characterized in our third note. Here, we are primarily interested in the model of bubble growth per se, and, of course, the appropriate simplification proposals [33]. Besides the conditions usual for such situations ideal gets, adherence to Henry s law, negligible mass of gas as compared to mass of liquid, absence of inertia, small Reynolds numbers, incompressibility of liquid, the authors postulated [33] several things that require discussion ... 

If the system is not isolated, its entropy may either increase or decrease. Thus, if a mass of gas is compressed in a cylinder impervious to heat, its entropy increases, but if heat is allowed to pass out into a medium, the entropy of the gas may decrease. By including the"gas and medium in a larger isolated system, we can apply (10) of 45, and hence show Jhat the medium gains more entropy than the gas loses. An extended assimilation of this kind shows that, if every body affected in a change is taken into account, the entropy of the whole must increase by reason of irreversible changes occurring in it. This is evidently what Clausius (1854) had in mind in the formulation of his famous aphorism The entropy of the universe strives towards a maximum. The word universe is to be understood in the sense of an ultimately isolated system. 

The isothermal expansion of an ideal gas is an aschistic process.— If a mass of gas expands isothermally, the heat absorbed is equal to the external work done. 

If Q is the heat absorbed in the vicinity of the plug, uA, nB> the internal energies of unit mass of gas in the states A and B, referred to some standard state as zero, then... 

If Mi is the mass of gas dissolved in a given volume of a liquid under unit pressure at a given temperature, np the mass dissolved under a pressure p, then, by Henry s law... 

At the other extreme, i.e., at high pressures, the mass of gas in a pocket determines the pocket size ... 

For an isothermal change in an ideal gas, the product of pressure and volume is a constant. For unit mass of gas ... 

The net work done by unit mass of gas on the surroundings in expanding from P to Pj is given by ... 

If during the compression of unit mass of gas, its volume changes by an amount du at a... 

It will be noted that the mass of gas in the cylinder varies during the cycle. The work done by the compressor during each phase of the cycle is as follows ... 

Thus, theoretically, the clearance volume does not affect the work done per unit mass of gas, since Vi — V4 is the volume admitted per cycle. It does, however, influence the quantity of gas admitted and therefore the work done per cycle. In practice, however, compression and expansion are not reversible, and losses arise from the compression and expansion of the clearance gases. This effect is particularly serious at high compression ratios. 

The same mass of gas passes through each of the cylinders and, therefore, if the interstage coolers are assumed perfectly efficient, the ratio of the volumes of gas admitted to successive cylinders is (P]/P2 ) / The volume of gas admitted to the second cylinder is then ... 

Whilst the calculation of the radiant heat flux from a gas to an adjoining surface embraces inherent spectral and directional effects, a simplified approach has been developed by Hottel and Manglesdorf 54, which involves the determination of radiation emission from a hemispherical mass of gas of radius L, at temperature 7, ... 

L Separation of surfaces, length of a side or radius of hemispherical mass of gas m L... 

Step 3 Substitute the data, if necessary converting from mass of gas to the amount in moles. Select the value of R... 

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