The gas constant is equivalent toBoltzmann constant, but expressed in energy units (i.e. pressure volume product) as per mole per temperature increment (rather than energy per particle per temperature increment).The constant is also a combination of Boyle's law, Charles's law, Avogadro's law and Gay Lussac's law.
Gas constant is a constant representing the thermodynamic properties of ideal gas.Is the ratio of the product of absolute pressure p and specific volume v of the ideal gas to the thermodynamic temperature T.It is usually represented by the symbol "R", and the unit is "J/(kg · K)".The gas constant is numerically equivalent to the expansion work made by an ideal gas with a mass of 1kg when the temperature increases by 1K during the reversible constant pressure heating process.Its value only depends on the type of gas and has nothing to do with the thermal state of the gas.For example, R of oxygen is always equal to 259.8J/(kg · K), R of nitrogen is always 296.7J/(kg · K), etc.In engineering thermodynamics and other disciplines, the general gas constant is usually divided by thousand molar mass orMayer’s formula To calculate and determine the gas constants of various ideal gases.[2]
Is the gas constant of the gas.R is calledUniversal gas constant, also known as universal gas constant, does not change with the change of molecular weight of gas;M is the molar mass of the gas.For example, hydrogen M=0.003016 kg/mol, then
。[3-4]
data
Announce
edit
RValue of
Company
eight point three one four four seven two
J/(K·mol)
zero point zero eight two zero five seven four five eight seven
L·atm/(K·mol)
8.20574587 × 10-5
mthree·atm/(K·mol)
eight point three one four four seven two
mthree·Pa/(K·mol)
eight point three one four four seven two
L·kPa/(K·mol)
8.314472 x 10six
cmthree·Pa/(K·mol)
sixty-two point three six three seven
L·mmHg/(K·mol)
sixty-two point three six three seven
L·Torr/(K·mol)
one point nine eight seven one eight
cal/(K·mol)
eighty-three point one four four seven two
L·mbar/(K·mol)
Related derivation
Announce
edit
Complementary R unit derivation:
fromIdeal gas equation of state: pV=nRT: R=pv/(nT) [where the unit of each quantity is p: pa, v: mthree， n： mol， T： k]
Carry in the unit for deduction: R []=pa · mthree/(mol · k) (pa · mthreeIt can be divided into: pa · mtwo·m. But F=PS knows pa · mtwoThat is NNewtonUnit, known from W=FS, N · m is the unit of work J), so the unit of R can be obtained through the above substitution: J/(mol · k).
American Standard Atmosphere
Announce
edit
In 1976, the gas constant R * was defined as:
R * = 8.31432×10threeN m kmol-1K-1。
Note that the use of kilomolar units results in a factor of 1000 in the constant.USSA1976 acknowledges that this value is inconsistent with the quoted value of Avogadro constant and Boltzmann constant.This difference is not a significant deviation from the accuracy. USSA1976 uses this R * value for all calculations of standard atmosphere.When the ISO value of R is used, the calculated pressure increases by 0.62 Pascal at 11km (equivalent to only 17.4 cm or 6.8 inch difference) and 0.292 Pascal at 20km (equivalent to only 0.338 m or 13.2 inch difference).[5]
