State the values of universal gas constant R in different units.
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Answer:
Gas constant
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Values of R[1] Units
SI Units
8.31446261815324 J⋅K−1⋅mol−1
8.31446261815324 m3⋅Pa⋅K−1⋅mol−1
8.31446261815324 kg⋅m2·K−1⋅mol−1s−2
8.31446261815324×103 L⋅Pa⋅K−1⋅mol−1
8.31446261815324×10−2 L⋅bar⋅K−1⋅mol−1
US Customary Units
0.730240507295273 atm⋅ft3⋅lb⋅mol−1°R−1
10.731557089016 psi⋅ft3⋅⋅lb⋅mol−1°R−1
1.985875279009 BTU⋅⋅lb⋅mol−1°R−1
Other Common Units
297.049031214 in. H2O⋅ft3⋅lb⋅mol−1°R−1
554.984319180 torr⋅ft3⋅lb⋅mol−1°R−1
0.082057366080960 L⋅atm⋅K−1⋅mol−1
62.363598221529 L⋅Torr⋅K−1⋅mol−1
1.98720425864083...×10−3 kcal⋅K−1⋅mol−1
8.20573660809596...×10−5 m3⋅atm⋅K−1⋅mol−1
8.31446261815324×107 erg⋅K−1⋅mol−1
The gas constant (also known as the molar gas constant, universal gas constant, or ideal gas constant) is denoted by the symbol R or R. It is equivalent to the Boltzmann constant, but expressed in units of energy per temperature increment per mole, i.e. the pressure–volume product, rather than energy per temperature increment per particle. The constant is also a combination of the constants from Boyle's law, Charles's law, Avogadro's law, and Gay-Lussac's law. It is a physical constant that is featured in many fundamental equations in the physical sciences, such as the ideal gas law, the Arrhenius equation, and the Nernst equation.
Physically, the gas constant is the constant of proportionality that relates the energy scale in physics to the temperature scale, when a mole of particles at the stated temperature is being considered. Thus, the value of the gas constant ultimately derives from historical decisions and accidents in the setting of the energy and temperature scales, plus similar historical setting of the value of the molar scale used for the counting of particles. The last factor is not a consideration in the value of the Boltzmann constant, which does a similar job of equating linear energy and temperature scales.
The gas constant R is defined as the Avogadro constant NA multiplied by the Boltzmann constant (kB or k):
{\displaystyle R=N_{\rm {A}}k_{,}\,}{\displaystyle R=N_{\rm {A}}k_{,}\,}
Since the 2019 redefinition of SI base units, which came into effect on 20 May 2019, both NA and k are defined with exact numerical values when expressed in SI units.[2] As a consequence, the value of the gas constant is also exactly defined, at precisely 8.31446261815324 J⋅K−1⋅mol−1.
Some have suggested that it might be appropriate to name the symbol R the Regnault constant in honour of the French chemist Henri Victor Regnault, whose accurate experimental data were used to calculate the early value of the constant; however, the origin of the letter R to represent the constant is elusive.[3][4]
The gas constant occurs in the ideal gas law, as follows:
{\displaystyle PV=nRT=mR_{\rm {specific}}T}{\displaystyle PV=nRT=mR_{\rm {specific}}T}
where P is the absolute pressure (SI unit pascals), V is the volume of gas (SI unit cubic metres), n is the amount of gas (SI unit moles), m is the mass (SI unit kilograms) contained in V, and T is the thermodynamic temperature (SI unit kelvins). Rspecific is the mass-specific gas constant. The gas constant is expressed in the same physical units as molar entropy and molar heat capacity.
Answer:
R = 0.0821 (lit atm) / (mol K)
R = 8.314 J / (mol K)
R = 8.314 x 10^7 erg / (mol K)
R = 2 cal / ( mol K)
Note:
In Problems use as,
0.0821 = 1 / 12 ( 1÷ 12)
8.314 = 25 / 3 (25÷3)
0.0821 = 22.4 / 273