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pure water at 3.984 °C, temperature of its maximum density (1.0000 g/cm 3) [24] 10 2: hM 118.8 M: pure osmium at 20 °C (22.587 g/cm 3) [25] 140.5 M: pure copper at 25 °C (8.93 g/cm 3) 10 3: kM: 10 4: 24 kM: helium in the solar core (150 g/cm 3 ⋅ 65%) [26] 10 5: 10 6: MM: 10 7: 10 8: 122.2 MM: nuclei in a white dwarf from a 3 M ...
Atmospheric pollutant concentrations expressed as mass per unit volume of atmospheric air (e.g., mg/m 3, μg/m 3, etc.) at sea level will decrease with increasing altitude because the atmospheric pressure decreases with increasing altitude. The change of atmospheric pressure with altitude can be obtained from this equation: [2]
PM is most usually (but not always) expressed as mg/m 3 of air or other gas at a specified temperature and pressure. For gases, volume percent = mole percent; 1 volume percent = 10,000 ppmv (i.e., parts per million by volume) with a million being defined as 10 6.
For example, the conversion factor between a mass fraction of 1 ppb and a mole fraction of 1 ppb is about 4.7 for the greenhouse gas CFC-11 in air (Molar mass of CFC-11 / Mean molar mass of air = 137.368 / 28.97 = 4.74). For volume fraction, the suffix "V" or "v" is sometimes appended to the parts-per notation (e.g. ppmV, ppbv, pptv).
The SI unit of molar absorption coefficient is the square metre per mole (m 2 /mol), but in practice, quantities are usually expressed in terms of M −1 ⋅cm −1 or L⋅mol −1 ⋅cm −1 (the latter two units are both equal to 0.1 m 2 /mol). In older literature, the cm 2 /mol is sometimes used; 1 M −1 ⋅cm −1 equals 1000 cm 2 /mol.
Conversion of units is the conversion of the unit of measurement in which a quantity is expressed, typically through a multiplicative conversion factor that changes the unit without changing the quantity. This is also often loosely taken to include replacement of a quantity with a corresponding quantity that describes the same physical property.
An overview of ranges of mass. To help compare different orders of magnitude, the following lists describe various mass levels between 10 −67 kg and 10 52 kg. The least massive thing listed here is a graviton, and the most massive thing is the observable universe.
The conversion procedure for some units (for example, the Mach unit of speed) are built into Module:Convert as they are too complex to be specified in a table. That is indicated by entering a code (which must be the same as used in the module) in the Extra column.