Mass percentages defined

Several measures are used to specify the composition of a solution. Mass percentage (colloquially called weight percentage), frequently used in everyday applications, is defined as the percentage by mass of a given substance in the solution. In quantitative chemistry, the most useful measures of composition are mole fraction, molarity, and molality. 

Rhodium mass balance, defined as the total amount of rhodium measured as a percentage of the starting amount (1235 pg). 

We often express the concentration of very dilute solutions in parts per million (ppm) or parts per billion (ppb). These quantities are similar to mass percentage but use 10 (a million) or 10 (a billion), respectively, in place of 100 as a multiplier for the ratio of the mass of solute to the mass of solution. Thus, parts per million is defined as... 

SECTION 13w4 Concentrations of solutions can be expressed quantitatively by several different measures, including mass percentage [(mass solute/mass solution) X 10 ], parts per milion (ppm), parts per bilion (ppb), and mole fraction. Molarity, M, is defined as moles of solute per liter of solution molaity, m, is defined as moles of solute per kg of solvent Molarity can be converted to these other concentration units if the density of the solution is known. 

Esser investigated the extraction of sulfur compounds from a model fuel using 50 ionic liquids in order to determine which are suitable. The criteria here were a low solubility of hydrocarbons in the ionic liquid, industrial availabiHty, and a high distribution coefficient Kn as a measure of the extraction efficiency [62], The distribution coefficient is defined as the ratio of the mass percentage of sulfur in the ionic liquid to the mass percentage of sulfur in the fuel in the state of equilibrium. Data for four powerful ionic liquids are given in Table 34.5. 

Suppose that A is a part of something—that is, part of a whole. It could be an element in a compound or one substance in a mixture. We define the mass percentage... 

Blending is the adjustment of defined mass percentages of several raw material components. It is achieved by the following processes ... 

The MEP is defined as the path of steepest descent in mass-weighted Cartesian coordinates. This is also called intrinsic reaction coordinate (IRC). In reality, we know that many other paths close to the IRC path would also lead to a reaction and the percentage of the time each path is taken could be described by the Boltzmann distribution. 

Pattemators may comprise an array of tubes or concentric circular vessels to coUect Hquid droplets at specified axial and radial distances. Depending on the pattemator, various uniformity indexes can be defined using the accumulated relative values between the normalized flow rate over a certain sector or circular region and a reference value that represents a perfectly uniform distribution. For example, using an eight-sector pie-shaped coUector, the reference value for a perfectly uniform spray would be 12.5%. The uniformity index (28) could then be expressed as foUows, where is the normalized volume or mass flow rate percentage in each 45-degree sector. 

The performance of any type of molecular separator is characterized in terms of its separation factor (enrichment) M and separator yield (efficiency) Y (8). The separator yield is defined as the ratio of the amount of sample entering the mass spectr( eter to that entering the separator, usually expressed as a percentage, it represents the ability of device to allow... 

The presence of one carbon atom in a molecule of carbon dioxide results in registration of the molecular ion peak of m/z 44 and of the A + 1 isotopic peak of m/z 45. The intensity of the latter is 1.1 % of that of M+. It appears due to the presence of 13C02 molecules. An increase in the number of carbon atoms in a molecule leads to an increase of the intensity of the M + 1 ion peak to 1.1 n% of M+, where n is the number of carbon atoms in the molecule. To calculate the number of carbon atoms in a molecule using a mass spectrum one should divide the intensity of the M + 1 peak as a percentage of M by 1.1. The result defines the maximum possible number of carbon atoms. One should remember that calculations may be more complicated if an [M — H]+ ion peak is present. 

Spectral analysis shows quite clearly that the various types of atoms are exactly the same on Earth as in the sky, in my own hand or in the hand of Orion. Stars are material objects, in the baryonic sense of the term. All astrophysical objects, apart from a noteworthy fraction of the dark-matter haloes, all stars and gaseous clouds are undoubtedly composed of atoms. However, the relative proportions of these atoms vary from one place to another. The term abundance is traditionally used to describe the quantity of a particular element relative to the quantity of hydrogen. Apart from this purely astronomical definition, the global criterion of metallicity has been defined with a view to chemical differentiation of various media. Astronomers abuse the term metaT by applying it to all elements heavier than helium. They reserve the letter Z for the mass fraction of elements above helium in a given sample, i.e. the percentage of metals by mass contained in 1 g of the matter under consideration. (Note that the same symbol is used for the atomic number, i.e. the number of protons in the nucleus. The context should distinguish which is intended.)... 

Quantitative characteristics of a macromolecule or an assembly of macromolecules, such as mass and mole fractions or percentages as well as the degrees of polymerization and molar masses, may be expressed by placing corresponding figures after the complete name. The order of citation is the same as for the monomer species in the name. Some characteristics cannot be defined for all types of macromolecules and assemblies dealt with in this document, e.g. molar mass of a network. 

If PMF and sequence homology searches fail using available protein and EST databases, mass spectrum data can, in principle, be used to search genome databases (GenBank http //www.ncbi.nlm.nih.gov/). However, only a small percentage of large genomic sequences code for proteins such that bioinformatics still needs to accurately define exon-intron structures (Andersen and Mann, 2000). 

Porosity is defined as the percentage of soil occupied by pore space and is an important parameter related to the transport, retardation, and mass transfer of pollutants in groundwater. 

The membrane swelling capacity (or gel water content) is defined as the percentage ratio of the difference between the mass of a wet sample (mw), equilibrated in deionized water for 2 days, and that of the same sample (mD), dried at 75°C over phosphorous oxide (P2O5) under vacuum, by mD (Strathmann, 1992). 

The molecular beam deflection method is shown schematically in Figure 3-17 (Buck et al. 1985). It is based on momentum transfer between clusters entrained in a molecular beam and rare gas atoms which are the constituents of a second molecular beam at 90° to the cluster beam. Collisions between the rare gas atoms and the clusters under single-collision conditions deflect a small percentage of the clusters from their original path. The maximum deflection angle depends on the mass of the cluster. For example, binary clusters may be deflected into a broad range of angles with a well defined upper limit set by the momentum conservation... 

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