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# AUnits, Physical Constants, and Conversion Factors

## Basic and Derived SI Units

 Quantity Unit Symbol Length meter m Mass kilogram kg Time second s Electric current ampere A Temperature kelvin K °C t/°C = T/K – 273.15 Amount of substance mole mol Force newton N = kg m s−2 Work, energy, heat joule J = N m Power watt W = J s−1 Pressure pascal Pa = N m−2 Frequency hertz Hz = s–1 Electrical charge coulomb C = A s Electrical potential volt V = J C−1 Electrical resistance ohm Ω = V A−1

## Physical Constants

 Constant Symbol Value Avogadro's number NA 6.022 × 1023 mol–1 Elementary charge e 1.602 × 10–19 C Electron rest mass me 9.109 × 10–31 kg Proton rest mass mp 1.673 × 10–27 kg Neutron rest mass mn 1.675 × 10–27 kg Atomic mass unit (dalton) amu (Da) 1.661 × 10–27 kg Gas constant R 8.315 J mol−1 K−1 Boltzmann's constant k = R/NA 1.381 × 10–23 J K−1 Planck's constant h 6.626 × 10–34 J s ℏ = h/2π 1.055 × 10–34 J s Standard acceleration of gravity g 9.807 m s−2 Speed of light c0 2.998 × 108 m s−1 Faraday constant F = eNA 9.649 × 104 C mol−1 Permeability of the vacuum μ0 4π × 10–7 N A−2 (exact) Permittivity of the vacuum ε0 = 1/μ0c02 8.854 × 10–12 C2 N−1 m−2

## Conversion Factors for Non‐SI Units

 1 dyne = 10–5 N 1 eV/particle = 96.48 kJ mol−1 1 bar = 105 Pa 1 D = 3.336 × 10−30 C m 1 atm = 1.013 bar 1 l = 1 dm3 = 10–3 m3 1 torr = 1/760 atm 1 cm−1 = 1.986 × 10–23 J 1 psi = 6.895 × 103 Pa hc/k = 1.438 cm K 1 int. cal = 4.187 J 1 l atm2 mol−1 = 101.3 J mol−1 1 erg = 10–7 J 1 eV = 1.602 × 10–19 J

## Prefixes

 pico p = 10–12 kilo k = 103 nano n = 10–9 mega M = 106 micro μ = 10–6 giga G = 109 milli m = 10–3 tera T = 1012

## Greek Alphabet

 A, α alpha N, ν nu B, β beta Ξ, ξ xi Γ, γ gamma O, o omicron Δ, δ delta Π, π pi E, ɛ epsilon P, ρ rho Z, ς zeta Σ, σ sigma H, η eta T, τ tau Θ, θ, ϑ theta ϒ, υ upsilon I, ι iota Φ, φ, ϕ phi K, κ kappa C, χ chi Λ, λ lambda Ψ, ψ psi M, μ mu Ω, ω omega

## Standard Values

 kT at 298 K = 207.2 cm−1 = 4.116 × 10–21 J = 2.569 × 10–2 eV = 2.479 kJ mol−1  = 0.5920 kcal mol−1 Standard molar volume at 298 K and 1 bar: Vm° = RT/P° = 2.479 × 10–4 m3 mol−1 Standard molar volume at 273 K and 1 atm: Vm° = RT/P° = 2.241 × 10–4 m3 mol−1 Standard pressure: P° = 1 bar = 105 N m−2
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