Conversion factor definition

Section 2 combines the former separate section on Mathematics with the material involving General Information and Conversion Tables. The fundamental physical constants reflect values recommended in 1986. Physical and chemical symbols and definitions have undergone extensive revision and expansion. Presented in 14 categories, the entries follow recommendations published in 1988 by the lUPAC. The table of abbreviations and standard letter symbols provides, in a sense, an alphabetical index to the foregoing tables. The table of conversion factors has been modified in view of recent data and inclusion of SI units cross-entries for archaic or unusual entries have been curtailed. 

Basic Standards for Chemical Technology. There are many numerical values that are standards ia chemical technology. A brief review of a few basic and general ones is given hereia. Numerical data and definitions quoted are taken from References 16—19 (see Units and conversion factors) and are expressed ia the International System of Units (SI). A comprehensive guide for the appHcation of SI has been pubUshed by ASTM (20). 

In summary, for engineering systems both F and M can be considered fundamental because of the engineering definition of weight in addition to Newton s second law. However, this results in a redundancy, which needs to be recified by the conversion factor gc. The value of this conversion factor in the various engineering units provides the following identities ... 

For quantitative considerations it is convenient to use atomic units (a.u.), in which h = eo = me = 1 (me is the electronic mass) by definition. They are based on the electrostatic system of units so Coulomb s law for the potential of a point charge is = q/r. Conversion factors to SI units are given in Appendix B here we note that 1 a.u. of length is 0.529 A, and 1 a.u. of energy, also called a hartree, is 27.211 eV. Practically all publications on jellium use atomic units, since they avoid cluttering equations with constants, and simplify calculations. This more than compensates for the labor of changing back and forth between two systems of units. 

APPENDIX R—SI TO U.S. UNITS CONVERSION FACTORS, SYMBOLS, DEFINITIONS, AND ABBREVIATIONS... 

Solve these kinds of problems by using the definition of molarity and conversion factors. In parts (b) and (c), you must first convert your mass in grams to moles. To do so, you divide by the molar mass from the periodic table (flip to Chapter 7 for details). In addition, be sure you convert milliliters to liters. 

The third-order nonlinear properties are specified in different ways by different authors and several systems of units are used. The conversions between different systems are not always obvious, as the numerical values of the conversion factors may depend on the definitions of particular properties. Table I lists some of the more important conversion factors and units. It should be noted that conversion of n2 values to /3) values can be performed using Eq. (4) in SI units. A frequently utilized conversion is that between n2 values in SI units (cm2 W1) and in cgs units (esu), namely n2 = (C]y3))/n2, where Q is approximately 0.039.7 Calculation of y values can be performed using Eq. (3). Reference 7 provides a discussion of the pitfalls that arise when applying conversion procedures between nonlinear properties defined in different ways. 

Length -definition of [MATERIALS STANDARDS AND SPECIFICATIONS] (Vol 16) -measurement of [UNITS AND CONVERSION FACTORS] (Vol 24)... 

Some numerical values are exact to as many significant figures as necessary, by definition. Included in this category are the numerical equivalents of prefixes used in unit definition. For example, 1 cm = 0.01 m by definition, and the units conversion factor, 1.0 x 10-2 m/cm, is exact to an infinite number of significant figures. 

Notice that our conversion factor between metric quantities has an interesting form. One side gets the prefix multiplier letter (in this case, the c ), and the other side gets the numerical equivalent of the multiplier (in this case, 1 x 10-2). Students sometimes get the number on the wrong side of the conversion factor. If you stick with the definition of the prefix multipliers given in Table 1.2, your conversion factors will always have a prefix multiplier on one side and a number on the other side. Seems fairer that way, doesn t it ... 

Unfortunately, however, there are several alternative definitions of ft and y (and higher hyperpolarizabilities) and many studies do not explicitly state which convention is being followed. Therefore, one should be careful in comparing values from different studies. These are discussed in detail, along with conversion factors, in Ref. [1], For example, the (n - l)th-order hyperpolarizability is commonly equated to (1/n ) X (dn i/dEn), rather than simply to the differential. 

Slight variations of the units described in this section have been used. Conversions factors can easily be derived on the basis of the definition of these alternative units. 

It is clear that with the definition of the Ampere also the other electrical quantities are defined. Thermodynamics required the introduction of the base quantities temperature and amount of substance, with the Kelvin and the mol as units. The unit of energy is the Joule, so that no conversion factor is involved here either. 

Mosse, J., Nitrogen to protein conversion factor for 10 cereals and 6 legumes or oilseeds—a reappraisal of its definition and determination—Variation according to species and to seed protein content. Journal of... 

Since 1893, the U.S. basis of length measurement has been derived from metric standards. In 1959, a small refinement was made in the definition of the yard to resolve discrepancies both in this country and abroad which changed its length from 3600/3937 m to 0.9144 m exactly. This resulted in the new value being shorter by two parts in a million. At the same time, it was decided that any data in feet derived from and published as a result of geodetic surveys within the U.S. would remain with the old standard (1 ft = 1200/3937 m) until further decision. This foot is named the U.S. survey foot. As a result, all U.S. land measurements in U.S. customary units will relate to the meter by the old standard. All the conversion factors in this table for units referenced to this footnote are based on the U.S. survey foot rather than on the international foot. 

We can avoid these conversion factors that relate the different rate expressions, by defining the rate in terms of an equivalent concentration instead of the molar concentration. If X is the number of equivalents per liter that reacted in a time t, then dX/dt is a convenient expression of the reaction rate. However, the definition of equivalent must be made explicit. 

Note Special density units called degrees Baume (°Be), degrees API (°API), and degrees Twaddell (°Tw) are occasionally used, particularly in the petroleum industry. Definitions of and conversion factors for these units are given on p. 1-20 of Perry s Chemical Engineers Handbook. 

The heat transfer was originally measured in units of calories, where one calorie was defined as the quantity of energy required to raise one gram of pure water from 14.5 to 15.5 °C at one atmosphere. This definition has been supplanted by the introduction of the joule, which represents the energy specified by the conversion factor 1 cal = 4.184 joules. One joule is also equivalent to the energy developed in a circuit by an electric current of one ampere flowing through a resistance of one ohm (driven by a potential difference of one volt) in one second. 

The SI is used throughout this book, as explained in the Preface. The system is reviewed in this appendix. Definitions and sufficient conversion factors are presented to enable the reader to understand the system, and to convert SI units to other common energy units used in the United States. Additional information is presented on the equivalencies of a few common U.S. energy units. 

In keeping with the older definitions of terms that are part of polarimetry, there are definitions for specific ellipticity [T ] = P.c. d, and molecular ellipticity [0] = [T ] M/lOO, where M is the molar mass. With appropriate substitutions, the molecular ellipticity can be expressed in terms of e, namely [0] = 3300(8/, Br) = 3300 Ae. The numerical constant is the result of all the physical conversion factors. 

A conversion factor begins with a definition of a relationship. The definition of one mole is... 

Note that different notations are used in the literature. Conversion factors between different definitions of the fundamental Planck scale can be found in Cavaglia 2003a. 

Conversion factors for mercury manometer pressure units are calculated using die standard value for the acceleration of gravity and die density of mercury at die stated temperature. Additional digits are not justified because the definitions of the units do not take into account die compressibility of mercury or the change in density caused by the revised practical temperature scale, ITS-90. Similar comments also apply to water manometer pressure units. Conversion factors for conventional mercury and water manometer pressure units are based on ISO 31-3. 

This section is designed to fill the gap between the familiar formulas presented above and the assumptions and definitions of terms and physical constants needed to apply them. Values for all physical constants and needed conversion factors are provided, and dimensional analyses are included to show how the final results and their units are obtained. This close focus on the details and units of the equations themselves is followed by worked examples from the chemical literature. The goal is to provide nearly everything the interested reader may need to evaluate his or her own data, with reasonable confidence that he or she is doing so correctly. 

According to the definition of mole, one mole of carbon-12 has a mass of 12 g, so the following conversion factor could be used to convert between mass of carbon-12 and moles of carbon-12. 

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