Compound mass fraction

Table 7.4 Typical mass fractions, w, of the halogenated products found in the combustion of organohalogen compounds [42,64]...

Solid PET feedstock for the SSP process is semicrystalline, and the crystalline fraction increases during the course of the SSP reaction. The crystallinity of the polymer influences the reaction rates, as well as the diffusivity of the low-molecular-weight compounds. The crystallization rate is often described by the Avrami equation for auto-accelerating reactions (1 — Xc) = cxp(—kc/"), with xc being the mass fraction crystallinity, kc the crystallization rate constant and n a function of nucleation growth and type. 

Elforts have been made to characterize the nature and content of individual components that are present in the low-molecular-mass fraction of the total mill effluents, which include the spent chlorination and alkali extraction stage liquors [2,4]. Approximately 456 types of compounds have been detected in the conventional bleach effluents, of which 330 are chlorinated organic compounds [22]. The compounds may be lumped into three main groups, namely, acidic, phenolic, and neutral (Table 2). Acidic compounds are further divided into the five categories of acids fatty, resin, hydroxy, dibasic, and aromatic acids. The most important fatty acids are formic and acetic acids. The dominant resin acids are abietic and dehydroabietic acids. Among the hydroxy acids identified, glyceric acid predominates. Dibasic acids such as oxalic, malonic, succinic, and mafic acids are derived from the lignin and carbohydrate fraction... 

Nitroguanidine (NQ) is a nitramine compound containing one N-NOj group in its molecular structure. In contrast to cyclic nitramines such as HMX and RDX, its density is low and its heat of explosion is also comparatively low. However, the Mg of its combustion products is low because of the high mass fraction of hydrogen contained within the molecule. Incorporating NQ particles into a double-base propellant forms a composite propellant termed a triple-base propellant, as used in guns. 

Polytetrafluoroethylene (Tf) is a polymeric fluorine compound that consists of a -C2F4- molecular structure,ini which contains a mass fraction of fluorine of 0.75. Tf is insoluble in water and its specific mass is in the range 3550-4200 kg nr in peUe-... 

It is convenient to select as the reference species, a non-reacting compound for which 0i =1, if such a species is present. This formulation, Eq. (17) is used because PAH concentrations are usually not reported on the mass fraction basis (mass of PAH per unit mass of particulate matter), but on an absolute basis (mass per unit volume of gas, pg/m ). 

Most studies of the chemical composition of particles in the troposphere to date have used analysis of bulk samples, which are usually collected in the boundary layer close to the earth s surface. As discussed in Chapter 6. J.3, there is a great deal of interest in the chemistry of the upper troposphere. Much less is known about the chemical composition in this region, particularly of particles. However, it appears that organics are also important constituents of particles in this region as well. For example, Novakov et al. (1997) in studies of particles both onshore and offshore of the eastern United States found that the mass fraction of the particles due to carbon compounds increased as a function of altitude. In the boundary layer, the fraction was typically 10-40%, increasing to 50-90%atan altitude of 2-3 km. 

In Eq. (C) FT j is the mass fraction of compound i in the exhaust from the test fuel, Fu, is the mass fraction of compound i in the exhaust from the base fuel, and MIR, is the maximum incremental reactivity of VOC i. Thus, a specific vehicle/test fuel combination with an RAF of 1.0 is expected to have the same contribution to ozone formation (in terms of specific reactivity, grams of 03 per gram of VOC exhaust emissions) as that vehicle operating on base gasoline. An RAF < 1.0 means that 1 g of the VOC exhaust emissions will form... 

The deposited sample also contains a mass mr of a R-containing compound (of molecular mass Mr), in which a mass fraction Jr of R exists. Then, the R-centered voltammetric signal should verify... 

It was shown that high molar mass lignosulfonate compounds can be fractionated by RPC into hydrophilic and hydrophobic compounds. It can be seen from Figures 4 and 5 that the birch lignosulfonates with low molar mass (fractions B and C in Figure 1) were also fractionated into hydrophilic and hydrophobic portions with no clearly resolved peaks. 

Fraction I, which is less hydrophobic than fractions III and V (Fig. 8), contains lower molar mass compounds than fraction III, which in turn contains lower molar mass compounds than the most hydrophobic fraction (fraction IV). 

Whereas TIMS suffers from the difficulties of time dependent mass fractionation in MC-ICP-MS, the mass fractionation is relatively constant. Its magnitude is often greater than that of TIMS and matrix effects are possible84. It is known that isotopic reference materials used for the calibration of isotope ratio measurements are available only as a pure metal or compound. Possible matrix effects during isotope ratio measurements, especially in solid-state... 

Among the congeners investigated was 2,2 ,5,5 -tetrachlorobiphenyl (TeCIBP), which was determined to be present in the Aroclor 1242 mixture at about 3.2 mass percent (i.e., mass fraction miAroclor = 0.032 g, -g jor). The measured aqueous concentrations for this compound were 1.11 pg L 1 (case a) and 0.10 pg-L"1 (case b), respectively. Are these concentrations reasonable What aqueous TeCIBP concentrations would you have predicted from the above information, when assuming that Raoult s law is valid in both cases ... 

Returning to the sorption observations (Fig. 9.7), as the mass fraction of organic carbon, foc, present in the solids approaches zero, the Kid values for both compounds become very small. Even at very lowy values. Q.,f0C = 0.001 kg oc-kg 1 solid), sorption to the organic components of a natural sorbent may still be the dominant mechanism (see Chapter 11). 

The mass fraction w(A) of a substance A in a mixture or of an element A in a compound is calculated using the formula... 

In order to determine the most important influences on the partition coming from the structures of the permeant molecules, 12 compounds have been selected from Table 9-7 and studied closer under different aspects. The selection contains compounds with different functional groups and molecular structures. An additional important criterion for the composition of this mixture is they can be easily separated into individual components by gas chromatography. By doing this, four to eight compounds could be measured simultaneously. Comparisons with measurements made using individual compounds showed no difference beyond measurement uncertainty, up to a concentration of 1 to 2 % (mass fraction) in methanol. 

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