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In chemistry, IUPAC changed its definition of standard temperature and pressure in 1982: [1] [2] Until 1982, STP was defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of exactly 1 atm (101.325 kPa).
historical definitions of the units and their derivatives used in old measurements; e.g., international foot vs. US survey foot. For some purposes, conversions from one system of units to another are needed to be exact, without increasing or decreasing the precision of the expressed quantity.
Isotherms of an ideal gas for different temperatures. The curved lines are rectangular hyperbolae of the form y = a/x. They represent the relationship between pressure (on the vertical axis) and volume (on the horizontal axis) for an ideal gas at different temperatures: lines that are farther away from the origin (that is, lines that are nearer to the top right-hand corner of the diagram ...
Conversions between units in the metric system are defined by their prefixes (for example, 1 kilogram = 1000 grams, 1 milligram = 0.001 grams) and are thus not listed in this article. Exceptions are made if the unit is commonly known by another name (for example, 1 micron = 10 −6 metre).
The relative activity of a species i, denoted a i, is defined [4] [5] as: = where μ i is the (molar) chemical potential of the species i under the conditions of interest, μ o i is the (molar) chemical potential of that species under some defined set of standard conditions, R is the gas constant, T is the thermodynamic temperature and e is the exponential constant.
For energy storage, the energy density relates the stored energy to the volume of the storage equipment, e.g. the fuel tank. The higher the energy density of the fuel, the more energy may be stored or transported for the same amount of volume. The energy of a fuel per unit mass is called its specific energy.
AMSTERDAM (Reuters) -The head of the chemical weapons watchdog said on Thursday he would ask Syria's new leaders to grant investigators access to the country to continue work identifying ...
And, indeed, the experimental values of c V,m for the noble gases helium, neon, argon, krypton, and xenon (at 1 atm and 25 °C) are all 12.5 J⋅K −1 ⋅mol −1, which is 3 / 2 R; even though their atomic weights range from 4 to 131. The same theory predicts that the molar heat capacity of a monatomic gas at constant pressure will be