Chemical quantities

Information Given by Chemical Equations Mole-Mole Relationships Mass Calculations The Concept of Limiting Reactants 

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More than ]Q billion pounds of methanol is produced annually. 

Suppose you work for a consumer advocate organization and you want to test a company s advertising claims about the effectiveness of its antacid. The company claims that its product neutralizes 10 times as much stomach acid per tablet as its nearest competitor. How would you test the validity of this claim  

After you study this chapter, you will be able to answer these questions. 

for an examination. Sean weighs Max and obtains a biood sampie for a biood chemistry profiie, which determines the overaii heaith, detects any metaboiic disorders, and measures the concentration of electrolytes. 

The results of the lab tests for Max indicate that the white blood count is elevated, which may indicate an infection or inflammation. His electrolytes, which are also indicators of good health, were all in the normal ranges. The electrolyte chloride (CP) was in the normal range of 0.106-0.118 mol/L, and the electrolyte sodium (Na ) has a normal range of 0.144-0.160 mol/L. Potassium (K ), another important electrolyte, has a normal range of 0.0035-0.0058 mol/L. To treat the possible infection, Sean ordered 375 mg tablets of Clavamox, which is a broad-spectrum antibiotic approved for veterinary use in dogs. 

Veterinarians care for domesticated pets such as rats, birds, dogs, and cats. Some veterinarians specialize in the treatment of large animals, such as horses and cattle. 

Veterinarians interact with pet owners as they give advice about feeding, behavior, and breeding. In the assessment of an ill animal, they record the animal s symptoms and medical history including dietary intake, medications, eating habits, weight, and any signs of disease. 

In chemistry, we calculate and measure the amounts of substances to use in the lab. Actually, measuring the amount of a substance is something you do every day. When you cook, you measure out the proper amounts of ingredients so that you don t have too much of one and too little of another. At the gas station, you pump a certain amount of fuel into your gas tank. If you paint the walls of a room, you measure the area and purchase the amount of paint that will cover the walls. If you take a pain reliever, you read the label to see how many tablets of aspirin or ibuprofen are needed. You read the nutrition label on food packaging to determine the quantities of carbohydrate, fat, sodium, iron, or zinc. 

I Doctors administering the polio vaccine in Niger. (Jean-Marc Giboux/Getty Images) 

OBJECTIVE To understand the molecular and mass information given in a balanced equation. 

Environmental scientists testing pond water for industrial pollutants. 

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Symbols separated by commas represent equivalent recommendations. Symbols for physical and chemical quantities should be printed in italic type. Subscripts and superscripts which are themselves symbols for physical quantities should be italicized all others should be in Roman type. Vectors and matrices should be printed in boldface italic type, e.g., B, b. Symbols for units should be printed in Roman type and should remain unaltered in the plural, and should not be followed by a full stop except at the end of a sentence. References International Union of Pure and Applied Chemistry, Quantities, Units and Symbols in Physical Chemistry, Blackwell, Oxford, 1988 Manual of Symbols and Terminology for Physicochemical Quantities and Units, Pure Applied Chem. 31 577-638 (1972), 37 499-516 (1974), 46 71-90 (1976), 51 1-41, 1213-1218 (1979) 53 753-771 (1981), 54 1239-1250 (1982), 55 931-941 (1983) lUPAP-SUN, Symbols, Units and Nomenclature in Physics, PV ica 93A 1-60 (1978). 

International Union for Pure and AppHed Chemistry (lUPAC) Bank Court Way, Cowley Centre Oxford 0X4 3YP United Kingdom Among its pubheations in the standards field are Manual of Symbols and Terminologyfor Physico-chemical Quantities and Units, D. H. Whiffen, ed., Pergamon, New York, 1979, and Nomenclature of Inorganic Chemisty, Pergamon, New York, 1977. 

SARATRAX irr Research institute, Maryland Technology Center Dr. Quon Y. Kwan Sr. Env. Engineer 4600 Forbes Blvd Lanham, MD 20706 (800) 4S8-1564 (301) 459-3711 Assists with delcrminalion of facility reporting responsibilities under Sections 301-303, 304, and 311-312. Assists with notification requirements and definitions of responsibilities. Maintains lists of chemicals, quantities, locations, and properties to assist with the preparation of Tier I and Tier 11 reports. Generates Form R. 

It is more common to express chemical quantities on a molar basis, and Eq. (5-31) becomes... 

The parameters and Ca are associated with the Lewis acid, and Eg and Cb with the base. a and b are interpreted as measures of electrostatic interaction, and Ca and Cb as measures of covalent interaction. Drago has criticized the DN approach as being based upon a single model process, and this objection applies also to the — A/y fBFs) model. Drago s criticism is correct, yet we should be careful not to reject a simple concept provided its limits are appreciated. Indeed, many very useful chemical quantities are subject to this criticism for example, p o values are measures of acid strength with reference to the base water. 

Multimedia models can describe the distribution of a chemical between environmental compartments in a state of equilibrium. Equilibrium concentrations in different environmental compartments following the release of defined quantities of pollutant may be estimated by using distribution coefficients such as and H s (see Section 3.1). An alternative approach is to use fugacity (f) as a descriptor of chemical quantity (Mackay 1991). Fugacity has been defined as fhe fendency of a chemical to escape from one phase to another, and has the same units as pressure. When a chemical reaches equilibrium in a multimedia system, all phases should have the same fugacity. It is usually linearly related to concentration (C) as follows ... 

Manual of symbols and terminology for physico-chemical quantities and units. Appendix III. Electrochemical nomenclature. Pure Appl. Chem., 37, 499 (1974). 

Measurement always involves comparison of an object with a suitable standard. Whereas physical elementary quantities like length and mass can be compared directly, chemical quantities are mostly compared indirectly. It... 

In Eq. (9.14), m — (xmax — xm[n)/(2Ax) represents the number of signal levels that can be distinguished significantly within the expectation range (see Fig. 9.3). The same holds for the number of the levels of the chemical quantity, e.g., concentration levels. This is valid on the pre-condition that all the m signal levels are equally probable, viz m is constant over the entire measuring range and, therefore, the standard deviation s=const, too. 

The core components of a complete microsystem are the integrated sensing, acting or passive micromechanical devices. In most cases, a naked chip manufactured in bulk or surface micromachining is used for the detection of a physical or chemical quantity or some actuation principle, like the dosage of ink droplets in inkjet printheads. A complete microsystem can consist of a complex set of these devices. 

The names and symbols of physical chemical quantities have also been recommended by the IUPAC [ 13]. It would be tedious to list even a minor fraction of the... 

There are several publications dealing with units and symbols of physical chemical quantities. Some also list the values of the fundamental physical constants, as recommended by the Committee on Data for Science and Technology (CODATA) in 2005 [1], The following tables contain the information that is relevant for molecular energetics [1,2]. 

The International Union of Puie and AppUed Chemistry now recommends a standard pressure of 0.1 MPa (1 bar) in place of the previously accepted standard of 101.325 kPa (1 atm). The difference in thermodynamic quantities is not significant for condensed phases, and differences in A// values are not significant even for gases, but the user of thermodynamic tables will have to note carefully the standard state chosen for any compilation of data. See Ref. 1, pp. 2—23 lUPAC Division of Physical Chemistry, Commission on Symbols, Terminology and Units, Manual of symbols and terminology for physico-chemical quantities and units, M. L. McGlashan, M. A. Paul, and D. N. Whiffen, eds., Pure andApp. Chem 51, 1 (1979), and Appendix IV, Pure and Applied Chem. 54, 1239 (1982). 

Since Pearson (7, 2) introduced the words soft and "hard in their new sense, there has been a persistent argument that it has something to do with electric dipole polarizabilities. Certainly, in most cases, the softness and high polarizabihty a run roughly parallel, in the same way as in many, but not all, cases, the soft ligands have low electronegativities. However, though a connection undoubtedly exists, a closer analysis of recent results (3) makes a a far more physical than chemical quantity. 

We often need to find the best estimate of a quantity from two or more separate and independent measurements of a single physical or chemical quantity. Suppose we have N separate measurements of a quantity x,... 

Long before, experience had already shown that such close relationships exist between some chemical (or physical) variables describing food composition that, for some characterizations, a combination of chemical or physical quantities is more meaningful than each quantity alone. Consequently, sums, ratios or ratios of sums of chemical quantities have been (and are being) studied to characterize food quality, origin or treatments. This search for useful features has been limited to combinations of a small number of variables, generally two, because of the limitations of the available computational facilities, until a few years ago. 

Secondly, the study of the chemical composition of foods and of its changes on processing are not the only aim (except in control analyses) the space of chemical quantities is intermediate between the cause space, which includes every parameter affecting food composition, and the effect space, where we find variables related to food properties, its quality, sensorial evaluations, nutritional value, and storage possibilities. Generally, the chemical space is described accurately and concisely. 

Among these methods, multicalibration (multivariate Calibration) is important. Multicalibration is the final development of indirect analytical methods. The analytical method has been previously defined as the whole of operational steps (reactions, separations,.. .) that lead to a highly selective endpoint where one measured physical variable is univocally related to one chemical variable (quantity, concentration,... ) this correlation is shown by the calibration curve (a straight line, generally). Multicalibration brinp a complete change of this definition the analytical method is the whole of chemical and mathematical operations that enable us to reach a multivariate selective system where several measured physical quantities are univocally related to several chemical quantities the correlation is shown by the calibration hypersurface. Multicalibration is surely destined to used with great effect in many areas in the future. 

Experimental results are generally grouped in tables two-dimensional matrices Xnv formed by N rows (objects = samples) and V columns (variables = chemical quantities, sensorial scores, physical quantities,. . . ). It is very difficult to read and understand the information contained in a large data matrix, therefore it is really... 

Knowing the relationships between chemical and sensorial variables, objective methods can be obtained to evaluate the food quality. Juries of experts cannot be formed and used so easily as the measurement of chemical quantities can. Besides, the knowledge of these relationships will be able to retain, so to speak, sensorial evaluations and follow the evolution of taste over a long period, so that it may be foreseen as well. 

In the following example, the measured chemical quantities are fixed by four continuous factors age, treatment A, treatment B and analytical error. Treatment B has been applied to only one sample of the class. Age and treatment A produce variations in composition that cannot be interpreted as deviations from the model they are the inner factors. On the other hand, treatment B cannot be identified as an inner factor because of the lack of information, and its effects fall, with the analytical error, in the outer space. Besides, if the effects of treatment B are noticeably greater than those of the analytical error, the B-treated object can be identified as an outlier, as it really is. 

Moll et al. searched for the optimum blending of malts when they are mashed. Because of the possibility of nonlinear interactions, a chemical quantity in the mixture cannot be simply considered a linear combination of each constituent. In the case of three malts, a full factorial design is used to obtain, by seven determinations, the seven coefficients a of the equation... 

It seems that there is a need to reexamine, some of the basic quantities used in transport processes, like Thiele numbers, attempting to connect them to more chemical quantities. For example, the macroscopic quantity, e the dielectric constant, can be interpreted in terms of dipole moment distribution, and the dipole moment has immediate structural implications. Now to talk of a dielectric constant in the interaction of two atoms would be a rather useless exercise, since the dilectric constant is a continuous matter concept, not a discrete matter concept. In the same... 

Typical values for the various physico-chemical quantities, as might be appropriate to a gaseous system, are given in Table 4.1. The initial conditions might be... 

This book combines information from a wide spectrum of disciplinary cultures, each having its own nomenclature and rules for how to express certain physical or chemical quantities. For example, in basic chemistry, particularly in physical chemistry, the rules are tough and everything is strictly regulated, whereas in physics, freedom of choice is rather large. Hence, one dilemma that we have to cope with in this book is to satisfy all these different worlds. 

In enzymology, binding constants of substrates or inhibitors of enzymes are estimated by registering the changes of CD the magnitudes induced at the wavelengths of the added molecules. This induced circular dichroism (ICD) depends on the binding mode and the chemical quantity of the bound molecules. This chemical measure is essential... 

The CMC is usually determined experimentally by plotting some property as a function of concentration and extrapolating the results at low and high concentrations to an intersection point. It is evident that the value obtained will depend on the type of representation used as well as on the physico-chemical quantity considered. For surfactants with low CMCs, micelle formation begins abruptly and the uncertainties involved are rather small while this is not always the case for surfactants with high CMCs. When the variation of CMC with chemical or physical factors is considered it is often essential to use CMC values obtained in a consistent way. 

This issue describes some of the many activities taking place today in the United States to develop measurement systems that will hopefully provide for traceability and or comparability of chemical measurements. Much of the activity is taking place in the private sector where we are seeing multiple approaches to measurement traceability and comparability both in the measurement of chemical quantities and in the production of reference materials. The extent to... 

Results of analytical chemistry are only valid within a reference system. Reference materials are the standards of analytical chemistry. They may be characterised for Identity (chemical structure) and for Property values (specific chemical quantities). 

Aris (3) more formally defined a mathematical model thus a system of equations, S, is said to be a model of prototypical system, S, if it is formulated to express the laws of S and its solution is intended to represent some aspect of the behavior of S. Seinfeld and Lapidus (4) gave a more specific definition Mathematical model is taken to mean the formulation of mathematical relationships, which describe the behavior of actual systems such that the dependent and independent variables and parameters of the model are directly related to physical and chemical quantities in the real system. ... 

Control of Potential and Measurement of Current. With the formulation of the laws of electrolysis by Michael Faraday in 1834, the basis for relating electrolysis currents to chemical quantities was established. Although the concept of electrolysis was known prior to then, its utility in terms of chemical analysis depended on a quantitative relationship between current and equivalents of substance. Because an electrolysis current always necessitates mass transfer to or away from the electrode, the formulation of equations for diffusion by Fick was an important event in developing quantitative relationships.1 With the laws of electrolysis and diffusion established, Heyrovsky combined these in a preferred form to provide a practical analytical method, namely, polarography.2 His real contribution beyond combining the important concepts of Faraday and Fick was to realize that a reproducible and continuously renewed... 

Density functional theory thus offers precise definitions of previously poorly defined chemical quantities, enabling their first principles calculation. This part of DFT is termed by Parr as conceptual DFT [6]. 

Furthermore, since we shall be dealing mainly with chemical quantities associated with the ambient, such a device will be concisely called an ambient chemical sensor (ACS). 

The importance of the characterization of the ambient, in terms of the measurements of those parameters capable of describing and/or controlling the ambient, is commonly recognized. These measurements can be done by special devices able to sense the physical or chemical quantities and possibly give an electric output signal. 

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