Combining ratio

Mendeleev noted patterns in the combining ratios of elements... 

The various chemistry combinations, ratios employed, and activity-levels offered give rise to an enormous number of possible permutations. Some common formulation examples include ... 

Low consumption rate relative to oxygen content (combining ratio)... 

The product feed rate is low, with a theoretical combining ratio of 1.24 1 in practice, however, it is used at 3 ppm per 1 ppm oxygen. 

Practical feed rates vary, but for a formulation containing, say, 10% erythorbate, the requirement is typically between 100 and 120 ppm whole product per 1 ppm 02. Consequently, this type of adjunct product may be expensive because of the high combining ratio required. 

As a result of this multistep process, the combining ratio varies. Assume 7.0 ppm HQ per 1 ppm oxygen. 

Note Combining ratio Ratio Pressure Distrib. tion... 

Unlike the crystalline cycloamylose complexes, combining ratios of host to guest in solution are usually 1 1. A notable exception is the interaction of the cycloamyloses with long chain aliphatic carboxylic acids. Solubility plots suggest that as many as four cycloheptaamylose molecules may interact with a single molecule of dodecanoic acid (Schlenk and Sand, 1961). In analogy to the crystalline state, cycloamyloses may form channels in solution in order to accomodate extended chains. 

As mentioned above, some chemistry of a few heavier elements is also of concern in the development of the geosphere and of living systems as we shall see later. A striking case is the chemistry of molybdenum (Mo) and tungsten (W), which we take here with vanadium (V). The first two elements are in the second and third series of transition metals and all three are found in higher combining ratios and with a greater preference for S rather than O, W less so than Mo (the... 

The dimensions of any given chunk of crystalline solid are determined by the environmental conditions under which it solidifies or is mechanically fractured. In the case of table salt, an average grain (0.1 mm ) contains about 10 atoms of Na and Cl. Thus, it is not possible to write one molecular formula that describes all grains of crystalline sodium chloride. Instead, chemists use an empirical formula that indicates the combining ratios of the atoms. For crystalline sodium chloride, this empirical formula is NaCl(s). 

Empirical formulae The molar combining ratio of a compound that has a variable size, such as a... 

Mineral An inorganic substance that occurs naturally in the Earth and has distinctive physical properties. Its chemical composition can be expressed as an empirical formula that shows the molar combining ratios of the constituent elements. 

Reaction between CF2and radicals has not been demonstrated in the gas phase but recently Mastrangelo65 has shown that -CF3 and CF2 trapped upon a liquid nitrogen cold finger, may interact on warming up to yield perfluoropropane and perfluorobutanc. Perfluoropropane has also been detected as a by-product in the photolysis of hexafluoroacetone. It is possible that all these reactions take place upon the walls of reaction vessels. 1,4-Dichlorooctafluorobutane was also detected in the high conversion photolyses but it was present only in trace quantities. From estimates of the concentration of these products, an approximate value for the disproportionation/combination ratio for -CFaCl radicals may be calculated. A value of 0.04 is obtained which is remarkably constant and independent of concentration and light intensity. 

Gunning66 has shown that disproportionation takes place when CF2C1 radicals are generated by the mercury-photosensitized decomposition of CF2CI2 and in recent studies confirming his results47 it was found that the disproportionation/combination ratio was again 0.04. 

The stoichiometry in anhydrous alcoholic media, as in aqueous media, is variable. The combining ratio for a stable adduct prepared at a low concentration of salt may often differ from the ratio obtained at a much higher concentration. The relationship between combining ratio and salt concentration will now be discussed in more detail. 

Senti and Witnauer1 have provided the only information yet available on the stoichiometry of formation of polysaccharide adducts. Their studies of addition compounds of amylose in aqueous ethanolic media showed that the combining ratio of D-glucose residue to salt is a function of salt concentration, and that the minimum ratios are approached as the salt concentration is increased. Beyond a certain concentration of salt, the ratio becomes almost constant. The anion plays an important role in determining the magnitude of the minimum ratio for an amylose adduct. Potassium bromide and potassium iodide give adducts of minimum ratio 2 1, whereas potassium acetate and potassium propionate give 1 1 adducts. A study of the composition of the potassium acetate adduct as a function of salt concentration indicated that two, relatively stable adducts are formed, the 1 1 and the 2 1. 

Adducts prepared in aqueous media generally possess one or more molecules of water of hydration per molecule, the number being a function of cation, anion, and the combining ratio of carbohydrate to salt. Available data on complexes of simple carbohydrates indicate that three molecules of water per molecule may be the maximum for adducts of alkali metal salts as many as seven have been reported for those of the alkaline-earth metal salts. Most complexes, however, possess only one or two molecules per molecule. Generally, the higher the combining ratio, the smaller is the number of water molecules that can be accommodated by a molecule of the adduct. 

The reaction of cellulose with aqueous lithium hydroxide is a continuous function of the hydroxide concentration, and gives no adducts of greatly favored combining ratio. Heuser and Bartunek101 isolated an adduct having a 1 2 ratio of lithium hydroxide to D-glucose residue. At the high concentration of 5 M lithium hydroxide,128 the ratio is 0.75 1. 

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