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The International Organization for Standardization (ISO), International Union of Pure and Applied Chemistry (IUPAC), and the International Union of Pure and Applied Physics (IUPAP) have jointly developed a set of recommended symbols for physical and chemical quantities. Consistent use of these recommended sym- bols helps assure unambiguous scientific communication. The list below is reprinted from Reference 1 with permission from IUPAC. Full details may be found in the following references: 1. Ian Mills, Ed., Quantities, Units, and Symbols in Physical Chemistry, Blackwell Scientific Publications, Oxford, 1988. 2. E. R. Cohen and P. Giacomo, Symbols, Units, Nomenclature, and Fundamental Constants in Physics , Document IUPAP–25, 1987; also published in Physica , 146A 1–68, 1987. 3. ISO Standards Handbook 2: Units of Measurement , International Organization of Standardization, Geneva, 1982. GENERAL RULES The value of a physical quantity is expressed as the product of a numerical value and a unit, e.g.: T = 300 K V = 26.2 cm 3 C p = 45.3 J mol -1 K -1 The symbol for a physical quantity is always given in italic (slop- ing) type, while symbols for units are given in roman type. Column headings in tables and axis labels on graphs may conveniently be written as the physical quantity symbol divided by the unit sym- bol, e.g.: T/K V /cm 3 C p /J mol -1 K -1 The values in the table or graph axis are then pure numbers. Subscripts to symbols for physical quantities should be italic if the subscript refers to another physical quantity or to a number, e.g.: C p – heat capacity at constant pressure B n – nth virial coefficient Subscripts which have other meanings should be in roman type: m p – mass of the proton E k – kinetic energy The following tables give the recommended symbols for the ma- jor classes of physical and chemical quantities. The expression in the Definition column is given as an aid in identifying the quantity but is not necessarily the complete or unique definition. The SI Unit gives one (not necessarily unique) expression for the coherent SI unit for the quantity. Other equivalent unit expressions, includ- ing those which involve SI prefixes, may be used. Name Symbol Definition SI unit Space and Time cartesian space coordinates x, y, z m spherical polar coordinates r, θ, φ m, 1, 1 generalized coordinate q, q i (varies) position vector r r = xi + y j + z k m length l m special symbols: height h breadth b thickness d, δ distance d radius r diameter d path length s length of arc s area A, A s , S m 2 volume V, (υ) m 3 plane angle α, β, γ, θ, φ… α = s/r rad, 1 solid angle ω, Ω ω = A/r 2 sr, 1 time t s period T T = t/N s frequency v, f v = 1/T Hz circular frequency, angular frequency ω ω = 2πv rad s –1 , s –1 characteristic time interval, relaxation time, time constant τ, T τ = | d t/ dln x| s angular velocity ω ω= d φ/ d t rad s –1 , s –1 velocity
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This note was uploaded on 02/04/2011 for the course CHEM 101 taught by Professor Dr.n during the Spring '10 term at McMaster University.

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