Relative molecular molar mass

Titanium dioxide [13463-67-7], chemical formula TiO and relative molecular molar mass of 79.8788, occurs in nature in three polymorphic crystal forms anatase, rutile, and brookite. Moreover, under high pressure, the structure of all three polymorphs of titanium dioxide may be converted into that of a-PbO. The main properties of the three polymorphs are... 

The relative molecular molar mass or simply the relative molar mass, denoted (formerly the molecular weight, MW) is a dimensionless quantity that corresponds to the ratio of the mass of the macromolecule to 1/12 of the mass of an atom of the nuclide C. It is the most important property of a macromolecule, because it is directly related to its physical... 

Also in the case of relatively low molar mass polystyrene (PS), the mass-resolved molecular ions in the MALDI-TOF spectra have provided information concerning the end-groups... 

The proportions of the various elements, n. n. n. n. n, must be rounded to the nearest integer to obtain the following empirical chemical formula C Hj,N O,S. Therefore, the relative molecular mass of the fuel, denoted M, can be easily calculated from the relative atomic molar mass of each chemical element, A, using the following equation ... 

The comparative results of Rxns 6 and 10 show that Sn(Oct)2 did not inhibit PDL polymerization. Comparison of Rxns 1 and 2 as well as 3 and 4 showed that high molecular weight copolymers could be formed by first polymerizing PDL with Novozyme 435 in the absence of L-lactide and Sn(Oct)2. Since Sn(Oct>2 did not inhibit Novozyme-435 catalyzed PDL polymerization, we believe L-lactide inhibits Novozyme-435 catalyzed PDL polymerization. In other words, the formation of low molar mass copolymers in Rxns. 1 and 3 and relatively higher molar mass copolymers in Rxns. 2 and 4 is directly related to the presence or absence of L-lactide in the reactions. Hence, the strategy of first performing Novozyme-435 catalyzed PDL polymerization and, subsequently, adding L-lactide to the reaction, is a way to circumvent L-lactide inhibition. Reactions 7 and 9 show that when Novozyme-435 is absent from the two-catalyst system, Sn(Oct)2 alone at 70°C was ineffective for PDL/L-lactide copolymerization and L-lactide homopolymerization, respectively. 

DIVEMA was the first synthetic polymer approved for clinical trials in cancer treatment, but initial tests in humans demonstrated unacceptable toxicity [27]. It was shown that the toxidty was due mainly to the molecular mass fractions with low molecular mass were inactive but nontoxic, while fractions with higher molecular mass were both active and toxic [14,16]. The clinical tests continued with a fraction of DIVEMA copolymer with relatively low molar mass (12000-15000 Da), named MVE-2, but it was proved not to be active [28,29]. The toxidty of the polymer was diminished by... 

Sodium chloride has a relative molecular mass of 58.44. A 0.1000M solution is prepared by weighing out 2.922 g of the pure dry salt (see Section 10.74) and dissolving it in 500 mL of water in a graduated flask. Alternatively about 2.9 g of the pure salt is accurately weighed out, dissolved in 500 mL of water in a graduated flask and the molar concentration calculated from the weight of sodium chloride employed. 

Throughout the main text of this book standard solutions and quantities have all been expressed in terms of molarities, moles and relative molecular masses. However, there are still many chemists who have traditionally used what are known as normal solutions and equivalents as the basis for calculations, especially in titrimetry. Because of this it has been considered desirable to include this appendix defining the terms used and illustrating how they are employed in the various types of determinations. 

The preferred term throughout this book is relative molar mass, but we should note that the use of this term is not common in polymer chenfistry. More often the older term molecular weight is used, both throughout the polymer industry and among acadenfic polymer scientists. This usage extends even to the current research literature. 

This equation appears to have a number of names, of which the Mark-Houwink equation is the most widely used. In order to use it, the constants K and a must be known. They are independent of the value of M in most cases but they vary with solvent, polymer, and temperature of the system. They are also influenced by the detailed distribution of molecular masses, so that in principle the polydispersity of the unknown polymer should be the same as that of the specimens employed in the calibration step that was used to obtain the Mark-Houwink constants originally. In practice this point is rarely observed polydispersities are rarely evaluated for polymers assigned values of relative molar mass on the basis of viscosity measurements. Representative values of K and a are given in Table 6.4, from which it will be seen that values of K vary widely, while a usually falls in the range 0.6-0.8 in good solvents at the 0 temperature, a = 0.5. 

M relative molar mass ( molecular weight ), amount of thermodynamic quantity... 

For molecular and ionic substances, one mole of any substance is its relative molecular mass or relative formula mass expressed in grams. This is called the molar mass, i.e. the mass in grams of one mole of a substance. 

Example A compound of nitrogen and hydrogen has an empirical formula NH2. The molar mass of the compound is 32 g mol-1. Calculate the molecular formula of the compound (relative atomic masses N = 14, H = 1). 

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