Conversion Factors for Energy Units

In this article both unsensitized and mercury vapor sensitized reactions are discussed. The plan has been to proceed from the chemically simplest system, oxygen molecule, to the chemically most complex, ozone plus hydrogen peroxide. Unless otherwise stated, thermochemical values have been taken from compilations of the National Bureau of Standards (68) and are reported in kcal. for the reaction represented in mole amounts. Conversion factors for energy units, spectroscopic notation, and unless noted, spectroscopically based values have been taken from... 

Tables for fundamental constants, conversion factors for energy units and entropy gases are presented in Chapter 8.

Conversion factors for energy units (from NBS Tables)... 

Appendix A gives an extensive table of conversion factors for energy as well as for other units. 

Section 7.1 gives examples illustrating the use of quantity calculus for converting the values of physical quantities between different units. The table in section 7.2 lists a variety of non-SI units used in chemistry, with the conversion factors to the corresponding SI units. Conversion factors for energy and energy-related units (wavenumber, frequency, temperature and molar energy), and for pressure units, are also presented in tables inside the back cover. 

Various units are used for expressing pressures (see Chapter 1, Footnote 8). A pressure of one standard atmosphere, or 0.1013 MPa, can support a column of mercury 760 mm high or a column of water 10.35 m high. As indicated in Chapter 1, the SI unit for pressure is the pascal (Pa), which is 1 N m-2 an SI quantity of convenient size for hydrostatic pressures in plants is often the MPa (1 MPa = 10 bar = 9.87 atm). (An extensive list of conversion factors for pressure units is given in Appendix II, which also includes values for related quantities such as RT.) Pressure is force per unit area and so is dimensionally the same as energy per unit volume (e.g., 1 Pa = 1 N m-2 = 1J m-3). Vw has the units of m3 mol-1, so VWP and hence /aw can be expressed in J mol-1. 

Conversion factors for energy-related units. 1973 CODATA constants... 

It is often necessary to convert the adopted value of a fundamental constant to another (SI or non-SI) unit. Useful conversion factors for energy equivalent quantities can be derived using the following relations ... 

Table 1.2. Conversion Factors for Energy and Mass Units 1 u = 1.6605656 X lO kg...

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. 

Energy Levels and Transition Probabilities of Some Atom of Photochemical Interest, 363 Conversion Factors for Absorption Cofficients, 373 Conversion Factors for Second Order Rate Constants, 37 1 Conversion Factors for Third Order Rate Constants, 374 Conversion from Pressure to Concentration Units, 375 Enthalpies of Formation of Atoms at 1 atm and 0°K in 11 . Idea Gas State, 375... 

Some conversion factors for the various units of work and energy are... 

In [Cu2] a is called the reproductive efficiency of the organism, since it is a ratio of the fraction of energy derived from uptake that is allocated to reproduction to the conversion factor relating food units to weight for reproduction (w/ is the amount of nutrient needed to produce one offspring). For similar reasons, 0 is called the growth efficiency of the organism. 

Two SI units refer to doses of radioactivity and these are used when calculating exposure levels for a particular source. The sievert (Sv) is the amount of radioactivity giving a dose in man equivalent to 1 gray (Gy) of v-rays 1 Gy = an energy absorption of 1 Jkg. The dose received in most biological experiments is a negligible fraction of the maximum permitted exposure limit. Conversion factors from older units are given in Table 35.3. 

Figure 7. Short-range behaviour of nuclear electrostatic potentials V r) (in atomic units) for different finite nuclear charge density distributions in the case of mercury, Z = 80, A = 200 (dashed curve PNC, solid curves FNCs). The FNC curves may be identified from their labels at the origin, see also Eq. (109). The corresponding charge density distributions are standardized to a common value of the rms radius, a 5.4590 fin, determined from Eq. (54). The ground state energies for Hg and Hg /i" (only PNC) are indicated, together with the lower continuum threshold for the relativistic one-electron states (horizontal dashed lines). In the present scale, the full spectrmn of bound electronic states practically coincides with the horizontal axis. The conversion factor from atomic units of length to femtometer is la.u. = 52917.7249frn, and the myon-electron mass ratio is = 206.768262 [1].

Conversion factors for mass, density, pressure, energy, specific energy, specific heat, thermal conductivity, dynamic viscosity, and kinematic viscosity in different systems of units are also given in Chap. 2 (Tables 2.1-2.9). 

TABLE 2.5 Conversion Factors for Units of Specific Energy... 

In presenting the experimentally observed spectrum, i.e., either the double differential scattering cross section d2a/dQdco or the dynamic structure factor S(q,a)) as a function of the energy exchange co, different workers often use different energy units for co. To facilitate conversion between these energy units, Table 8.1 gives the relationships between them. 

Conversion Factors for Thermal Energy and per Unit Time (Power)... 

Conversion factors for a few other units, which are not related to SI but which are necessary to read the existing literature, are as follows. One atomic unit of length equals 0.52918 Angstroms (A). One atomic unit of dipole moment (two unit charges separated by ao) equals 2.5418 Debyes (D), and one atomic unit of energy equals 27.211 electron volts (eV) or 627.51 kcal/mole. 

---