Formula weight, definition

Structural Formula Not definitely known has a molecular weight of about 3,300, a nitrogen content of about 7% and a carbohydrate content of 16 to 17%. 

The equivalent weight of an ion (or an element) is the ratio of its formula weight to its valence. According to an alternative definition that is also suitable for compounds, an equivalent weight represents the amount of a substance which will react with one atomic weight of hydrogen or its chemical equivalent. 

The term mole was first introduced by Wilhelm Ostwald in 1901. It is derived from the Latin for mass, hump, or pile (the term molecule, introduced by Pierre Gassendh in the early seventeenth century has the same root presumably it means a mass of atoms). Specifically, Ostwald used the term to represent the formula weight of a substance in grams 36.5 g of HCl is one mole. The formal definition of the mole adopted by the Fourteenth Conference Generale des Poids et Mesures in 1971 is the amount of a substance of a system that contains as many elementary entities as there are atoms in 0.012 kilograms of carbon-12. The rich irony is that Ostwald fiercely resisted the atomic concept at the time Boltzmann committed suicide in 1906 but his mole is now defined explicitly in terms of atoms. 

In principle, the conventions used for nonelectrolyte solutions developed in Chap. 11 could be employed for electrolyte solutions which are subject to the condition of electroneutrality. Agreement with experimental data could be obtained by choosing the molecular weight to be some fraction of the formula weight. However, these conventions generally lead to activity coefficients which are rapidly varying functions of composition. In order to avoid this, we formally define chemical potentials and activity coefficients for ionic components. The definition of chemical potentials for ionic components does not have operational significance since their concentrations cannot be varied independently. 

Formula weight 101.5. Small, needle-shaped crystals, which are unstable and therefore cannot be stored for any length of time. Caution should be exercised in handling NH ClOg since the substance occasionally explodes without apparent cause. It is definitely explosive at temperatures above 100°C. If the material is spread in a thin layer in the open, it may be manipulated without danger. It readily dissolves in water. 

Formula weight (HgPtCla 6 H3O) 518.0. Commercial platinum chloride containing 39.5-40% Pt is not a definite hydrate, but has the composition of HaPtCla 4.5 H3O and is deep orange. Starting material for the preparation of most platinum compounds. 

Again, we use carefully written unit factors from the stated molarity of (COOH)2,the reaction ratio, the formula weight of (C00H)2, and the definition of percentage to solve this problem.The percentage is reasonable (less than 100%). 

Pure sodium chloride, like pure water, has a definite melting (freezing) temperature (at a given pressure). Separating operations—such as distilling or freezing—do not separate the salt into components. The composition of the salt, whether expressed in relative numbers of sodium and chlorine atoms or in the relative weights of these atoms, is fixed and is represented by the formula NaCl. Sodium chloride, like water, is an example of a pure substance. 

Most people believe someone is obese if they look fat. This is not true. Health-care professionals and scientists have developed specific definitions for the words overweight and obese. Overweight and obesity are not determined solely by an individual s weight, but are defined in terms of a person s weight relative to his or her height. Doctors and researchers use a special set of measurements and mathematical formulas to determine whether a person is overweight or obese. 

Dalton s Law of Multiple Proportions meant that two elements combine in simple whole number ratios. Dalton believed that compounds found in nature would be simple combinations. Hence, knowing that hydrogen combines with oxygen to give water, Dalton s formula for water would consist of 1 H and 1 O. Its formula would be HO using modern nomenclature. Both Proust s Law of Definite Proportions and Dalton s Law of Multiple Proportions are outcomes of an atomic view of nature. In 1808 Dalton published his table of relative atomic weights along with his ideas on atomism in A New System of Chemical Philosophy. 

This formula is the VB analogue of the Mulliken population in MO-based calculations. The VB weights sum to unity if the wave function 1P, in Equation 3.54, is normalized. However, Equation 3.55 can be used even if the VB structures are not normalized, or even if represents an AO-based determinant rather than a VB structure. In such a case, it is useful to note that with the definition of the weights as in the Chirgwin—Coulson formula, the weight of a VB structure is equal to the sum of the weights of its constituting VB determinants. 

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