Gases relative density

Density is the most commonly measured property of a gas, and is obtained experimentally by measuring the specific gravity of the gas (density of the gas relative to air = 1). As pressure increases, so does gas density, but the relationship is non-linear since the dimensionless gas compressibility (z-factor) also varies with pressure. The gas density (pg) can be calculated at any pressure and temperature using the real gas law ... 

K Density of gas relative to its density Dimensionless Dimensionless Dimensionless... 

ISO, Natural Gas—Calculation of Calorific Value, Density and Relative Density International Organization for Standardization ISO 6976-1983(E). 

Vapor Density (VD) — the mass per unit volume of a given vapor/gas relative to that of air. Thus, acetaldehyde with a vapor density of 1.5 is heavier than air and will accumulate in low spots, while acetylene with a vapor density of 0.9 is lighter than air and will rise and disperse. Heavy vapors present a particular hazard because of the way they accumulate if toxic they may poison workers if nontoxic they may displace air and cause suffocation by oxygen deficiency if flammable, once presented with an ignition source, they represent a fire or explosion hazard. Gases heavier than air include carbon dioxide, chlorine, hydrogen sulfide, and sulfur dioxide. 

The relative density (with respect to air) has no units, so that the units of the Wobbe number are the same as calorific value. The value for gas is 49.79 MJ/m. ... 

Flow in a straight horizontal steel pipe (to BS 1387, Table 2, Medium) with 1.0 mhar differential pressure between the ends, for gas of relative density 0.6 (air = 1)... 

Abstract Sonoluminescence from alkali-metal salt solutions reveals excited state alkali - metal atom emission which exhibits asymmetrically-broadened lines. The location of the emission site is of interest as well as how nonvolatile ions are reduced and electronically excited. This chapter reviews sonoluminescence studies on alkali-metal atom emission in various environments. We focus on the emission mechanism does the emission occur in the gas phase within bubbles or in heated fluid at the bubble/liquid interface Many studies support the gas phase origin. The transfer of nonvolatile ions into bubbles is suggested to occur by means of liquid droplets, which are injected into bubbles during nonspherical bubble oscillation, bubble coalescence and/or bubble fragmentation. The line width of the alkali-metal atom emission may provide the relative density of gas at bubble collapse under the assumption of the gas phase origin. 

The blue satellite peak associated with resonance line of rubidium (Rb) saturated with a noble gas was closely examined by Lepoint-Mullie et al. [10] They observed SL from RbCl aqueous solution and from a 1-octanol solution of rubidium 1-octanolate saturated with argon or krypton at a frequency of 20 kHz. Figure 13.4 shows the comparison of the SL spectra of the satellite peaks of Rb-Ar and Rb-Kr in water (Fig. 13.4b) and in 1-octanol (Fig. 13.4c) with the gas-phase fluorescence spectra (Fig. 13.4a) associated with the B —> X transition of Rb-Ar and Rb-Kr van der Waals molecules. The positions of the blue satellite peaks obtained in SL experiments, as indicated by arrows, exactly correspond to those obtained in the gas-phase fluorescence experiments. Lepoint-Mullie et al. attributed the blue satellites to B — X transitions of alkali-metal/rare-gas van der Waals species, which suggested that alkali-metal atom emission occurs inside cavitating bubbles. They estimated the intracavity relative density to be 18 from the shift of the resonance line by a similar procedure to that adopted by Sehgal et al. [14],... 

Fig. 12.14. Metallicity evolution in DLAs. Curves show predicted mean metallic-ity in the interstellar gas relative to solar predicted by chemical evolution models of Pei, Fall and Hauser (1999), Pei and Fall (1995), Malaney and Chaboyer (1996) and Somerville, Primack and Faber (2001) respectively. Data points giving column-density weighted metallicities based on zinc only (filled circles) or other elements (open circles) are plotted in the upper panel taking upper limits as detections and in the lower panel taking upper limits as zeros. Horizontal error bars show the redshift bins adopted. After Kulkarni et al. (2005).

Vapor density is the measure of the relative density of the pure vapor or gas when compared to air. Technically it is the weight of a vapor per unit volume at any given temperature and pressure. Vapors with a vapor density of greater than 1.0 are heavier than air and will follow the surface of the ground until dissipated. Vapors with a vapor density less than 1.0 will rise into the atmosphere, the lower the density the faster they will rise. 

From a consideration of the relative densities, we expect the liquid phase to reside at the bottom of the container, with the less-dense gaseous phase floating above it. The critical point is reached when the density of the gas has increased until it becomes the same as that of the liquid. In consequence, there is now no longer a lighter and a heavier phase, because P(iiquid) = P(vapour)-Accordingly, we no longer see a meniscus separating liquid at the bottom of the container and vapour above it it is impossible to see a clear distinction between the liquid and gas components. We say that the C02 is critical. 

Natural Gas—Calculation of Calorific Values, Density, Relative Density and Wobbe Index from Composition. ISO 6976 1995(E). 

Olefins or alkenes are defined as unsaturated aliphatic hydrocarbons. Ethylene and propylene are the main monomers for polyolefin foams, but dienes such as polyisoprene should also be included. The copolymers of ethylene and propylene (PP) will be included, but not polyvinyl chloride (PVC), which is usually treated as a separate polymer class. The majority of these foams have densities <100 kg m, and their microstructure consists of closed, polygonal cells with thin faces (Figure la). The review will not consider structural foam injection mouldings of PP, which have solid skins and cores of density in the range 400 to 700 kg m, and have distinct production methods and properties (456). The microstructure of these foams consists of isolated gas bubbles, often elongated by the flow of thermoplastic. However, elastomeric and microcellular foams of relative density in the range 0.3 to 0.5, which also have isolated spherical bubbles (Figure lb), will be included. The relative density of a foam is defined as the foam density divided by the polymer density. It is the inverse of the expansion ratio . 

Powders are porous materials and their bulk and relative densities can change with consolidation (6). However, a powder s true density is the density of its solid phase only and thus is independent of the state of consolidation. The true density of organic excipients typically ranges from 1.0 to 1.6g/cm3 while inorganic excipients (e.g., calcium phosphate) show values greater than 2g/cm3. True density is used to determine powder or compact solid fraction (SF) (see below) and it may be a consideration when selecting excipients if segregation is a concern. True density is often determined by gas pycnometry. 

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