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Extended data list for water

Important constants and conversion factors


Values for some physical constants
Constant Value
Ångström
0.1 nm (exactly)
Standard atmosphere (that is, 1 atm)
101.3250 kPa (exactly) =1.013250 bar (exactly) = 760 torr (exactly)
= 1.03323 kg(force) cm-2
Avogadro number (NA)
6.02214179 x 1023 mol-1 [934]
Boltzmann constant (kB)
1.380 6504 x 10-23 J K-1 [934]
Thermal energy (kT at 298 K)
2.478 kJ mol-1
Celsius zero point (0°C exactly)
273.15 K (exactly; a degree Celsius has the same size as one kelvin)
Becquerel (Bq, unit of radioactivity)
One nuclear disintegration per second (1 Curie (Ci) = 3.7x1010 Bq, exactly)
Debye (D)
3.33564095 x 10-30 C m (= -0.20819435 e- Å)
e (base for natural logarithms)
Electron volt (eV)
96.4853399 kJ mol-1 (Faraday = 96,485.3399 C mol-1) [934]
Elementary charge (e)
-1.602176487 x 10-19 C [934]
Fahrenheit temperature scale (°F, obsolete)
(Fahrenheit temperature) = (Kelvin temperature) × 9⁄5 − 459.67
(Kelvin temperature) = (Fahrenheit temperature + 459.67) × 5⁄9
Acceleration due to gravity (g, standard)
9.80665 m s-2 (exactly)
1.618033988749894848204586834365638117720309179805...
Terahertz (THz)

1012 s-1 (1 ps-1 equivalent to 33.355640952 cm-1 = 299.792458 µm equivalent to 0.0041356692 eV equivalent to 399.03166 J mol-1)

Loge(10)
Kelvin (K)
The fraction 1/273.16 of the thermodynamic temperature of the triple point of water
Kilocalorie (kcal, thermochemical)
4.1840 kJ (exactly)
Molar gas constant (R = kNA)
8.314472 J mol-1 K-1 [934]
Permeability of a vacuum (µ0)
1.2566370614 µH m-1 (= 4π x 10-7 H m-1 exactly)
Permittivity of a vacuum (ε0)
8.854187817 pF m-1 (exactly) [934]
Planck constant (h)
6.6260696 x 10-34 J s
Π (= circle circumference/diameter)
Speed of light in vacuum
2.99792458 x 108 m s-1 (exactly, also defines the meter) [934]

 

Note that the  SI unit definitions are under review for change in 2011; for example, the kelvin may be redefined in terms of an exactly defined value for the Boltzman constant and the kilogram may be defined in terms of its energy content [1031].

 

 

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This page was last updated by Martin Chaplin on 20 October, 2008


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