Universal and Individual Gas Constants (2024)

Table of Contents
The Universal and Individual Gas Constants in fluid mechanics and thermodynamics. Individual gas constants for the most common gases. The Individual Gas Constant - R The Universal Gas Constant - R u The Universal Constant defined in Terms of the Boltzmann's Constant The Molecular weight of a Gas Mixture The Universal Gas Constant - R u - in alternative Units Related Topics Air Psychrometrics Fluid Mechanics Gases and Compressed Air Material Properties Related Documents Acetone - Thermophysical Properties Air - Molecular Weight and Composition Air - Thermophysical Properties Benzene - Thermophysical properties Dry Air - Thermodynamic and Physical Properties Ethylene - Thermophysical Properties Gas Mixtures - Properties Gases - Dynamic Viscosities Gases - Molar Specific Heats Gases - Ratios of Specific Heat Humid Air and the Ideal Gas Law Moist Air - Mole Fraction of Water Vapor Nitrogen - Enthalpy, Internal Energy and Entropy vs. Temperature Non-ideal gas - Van der Waal's Equation and Constants Rankine Efficiency Sulfur Dioxide Liquid - Thermal Properties Temperature The Ideal Gas Law Thermodynamic Terms - Functions and Relations Total and Partial Pressure - Dalton's Law of Partial Pressures Water-Steam Mollier Diagram Search Engineering ToolBox - SketchUp Extension - Online 3D modeling! Translate this Page Privacy Policy Advertise in the ToolBox Citation FAQs

The Universal and Individual Gas Constants in fluid mechanics and thermodynamics. Individual gas constants for the most common gases.

The Universal and Individual Gas Constants are known from the Ideal Gas Law .

The Individual Gas Constant - R

The Individual Gas Constant depends on the particular gas and is related to the molecular weight of the gas. The value is independent of temperature. The induvidual gas constant, R, for a gas can be calculated from the universal gas constant, R u ( given in several units below ), and the gas molecular weight, M gas :

R = R u /M gas [1]

In the imperial system the most common units for the individual gas constant are ft lb/slug o R . In the SI system the most common units are J/kg K .

Unit conversion: 1 J/kg K = 5.97994 ft lb/slug °R, and 1 ft lb/slug °R = 0.167226 J/kg K.

The Individual Gas Constant for gases:

For full table - rotate the screen!

Individual Gas Constants
Gas Molecular
Weight 		Individual Gas Constant - R
Name Formula [g/mol],
[kg/kmol] 		[J/kg K] [kJ/kg K] [Wh/(kg K)] [kcal/(kg K)],
[Btu(IT)/lb °F] 		[kcal/(lb °F)] [ft lbf /lb °R] [ft lbf /slug °R]
AcetyleneC2H 2 26.038 319.32 0.31930.088700.076270.062359.350 1910
Air A mixture 28.9647 287.05 0.28710.079740.068560.056053.353 1717
AmmoniaNH317.031 488.21 0.48820.135610.116610.095290.740 2919
ArgonAr39.948 208.13 0.20810.057810.049710.040638.684 1245
ButaneC 4 H 10 58.122 143.05 0.14310.039740.034170.027926.588 855
ButeneC 4 H 8 56.106 148.19 0.14820.041160.035390.028927.543 886
Carbon DioxideCO 2 44.010 188.92 0.18890.052480.045120.036835.114 1130
Carbon MonoxideCO28.010 296.84 0.29680.082460.070900.057955.171 1775
Carbonic acidH2CO362.025 134.05 0.13410.037240.032020.026124.915 802
ChlorineCl 2 70.906 117.26 0.11730.032570.028010.022921.794 701
ChloromethaneCH3Cl50.488 164.68 0.16470.045750.039330.032130.608 985
DichlorofluorumethaneCHCl2F102.923 80.78 0.08080.022440.019290.015815.015 483
EthaneC2H630.069 276.51 0.27650.076810.066040.053951.393 1654
EtheneC2H 4 28.053 296.38 0.29640.082330.070790.057855.086 1772
FluorineF 2 37.997 218.82 0.21880.060780.052260.042740.670 1309
HeliumHe4.003 2077.1 2.07710.576960.496100.4050386.047 12421
HydrogenH 2 2.016 4124.2 4.12421.145630.985060.8043766.541 24663
Hydrogen bromideHBr80.912 102.76 0.10280.028540.024540.020019.099 614
Hydrogen chlorideHCl36.461 228.04 0.22800.063340.054470.044542.384 1364
Hydrogen sulfideH2S34.081 243.96 0.24400.067770.058270.047645.344 1459
KryptonKr83.798 99.22 0.09920.027560.023700.019318.441 593
Methane (natural gas)CH 4 16.042 518.28 0.51830.143970.123790.101196.329 3099
NeonNe20.180 412.02 0.41200.114450.098410.080376.579 2464
NitrogenN 2 28.013 296.80 0.29680.082450.070890.057955.165 1775
Nitrogen dioxideNO 2 46.006 180.73 0.18070.050200.043170.035233.590 1081
Nitrogen trifluorideNF371.002 117.10 0.11710.032530.027970.022821.765 700
Nitrous oxideN2O44.012 188.91 0.18890.052480.045120.036835.112 1130
OxygenO 2 31.999 259.84 0.25980.072180.062060.050748.294 1554
PropaneC3 H 8 44.096 188.56 0.18860.052380.045040.036835.045 1128
PropeneC3 H642.080 197.59 0.19760.054890.047190.038536.724 1182
Sulfur dioxideSO 2 64.064 129.78 0.12980.036050.031000.025324.122 776
Sulfur hexafluorideSF6146.055 56.93 0.05690.015810.013600.011110.581 340
Sulfur trioxideSO380.063 103.85 0.10380.028850.024800.020319.302 621
Water vaporH2O18.015 461.52 0.46150.128200.110230.090085.780 2760
XenonXe131.293 63.33 0.06330.017590.015130.012311.770 379

The Universal Gas Constant - R u

The Universal Gas Constant - R u - appears in the ideal gas law and can be expressed as the product between the Individual Gas Constant - R - for the particular gas - and the Molecular Weight - M gas - for the gas, and is the same for all ideal or perfect gases :

R u = M gas R [2]

The Universal Constant defined in Terms of the Boltzmann's Constant

The universal gas constant can be defined in terms of Boltzmann's constant k as:

R u = k N A [3]

where
k = Boltzmann's constant = 1.381 x 10 -23 [J/K]
N A = Avogadro Number = 6.022 x 10 23 [1/mol]

The Molecular weight of a Gas Mixture

The average molecular weight of a gas mixture is equal to the sum of the mole fractions of each gas multiplied by the molecular weight of that particular gas:

M mixture = Σx i *M i = (x1 *M1 + ......+ x n *M n ) [4]

where

x i = mole fractions of each gas
M i = the molar mass of each gas

The Universal Gas Constant - R u - in alternative Units

  • atm.cm3 /(mol.K) : 82.057338
  • atm.ft3 /(lbmol.K) : 1.31443
  • atm.ft3 /(lbmol. o R) : 0.73024
  • atm.l/(mol.K) : 0.0820 57338
  • bar.cm3 /(mol.K) : 83.144598
  • bar.l/(mol.K) : 0.083144 598
  • Btu/(lbmol. o R) : 1.9872036
  • cal/(mol.K) : 1.9859
  • erg/(mol.K) : 83144 598
  • hp.h/(lbmol. o R) : 0.0007805
  • inHg.ft3 /(lbmol. o R) : 21.85
  • J/(mol.K) :8.3144598
  • kJ/(kmol.K) : 8.3144598
  • J/(kmol.K) : 8314.472
  • (kgf/cm2).l/(mol.K) : 0.084784
  • kPa.cm3 /(mol.K) : 8314.4 598
  • kWh/(lbmol. o R) : 0.000582
  • lbf.ft/(lbmol. o R) : 1545.349
  • mmHg.ft3 /(lbmol.K) : 999
  • mmHg.ft3 /(lbmol. o R) : 555
  • mmHg.l/(mol.K) : 62.363577
  • Pa.m3 /(mol.K) : 8.3144 598
  • psf.ft3 /(lbmol. o R) : 1545.3465
  • psi.ft3 /(lbmol. o R) : 10.73
  • Torr.cm3 /(mol.K) : 62364

See also:
- More material properties
- The Ideal Gas Law - Gases are highly compressible with changes in density directly related to changes in temperature and pressure.
- A Mixture of Gases - Properties of mixtures of gases.
- More about temperature

Related Topics

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  • Fluid Mechanics

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  • Gases and Compressed Air

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  • Material Properties

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    Chemical, physical and thermal properties of acetone, also called 2-propanone, dimethyl ketone and pyroacetic acid. Phase diagram included.

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Universal and Individual Gas Constants (2024)

FAQs

What is the universal constant of gas value? ›

The gas constant value is given by R = 8.3144598(48) J⋅mol^−1⋅K^−1.

View Details ›
What is the constant of the universal gas law? ›

The gas constant R is 8.314 J / mol·K. Convert the numerical value of R so that its units are cal / (mol·K). A unit conversion table will tell you that 1 cal = 4.184 J.

Show Me More ›
What is the difference between gas constant and universal gas constant? ›

Difference between the universal gas constant and the characteristic gas constant. Universal gas constant is only applied for an ideal gas. A characteristic gas constant is applied for a real gas. Universal gas constant is calculated using standard temperature and the pressure (STP) values.

See Details ›
What is universal and individual gas constant? ›

Gas Constant (R)

The gas constant for an individual gas is the universal gas constant divided by the molecular weight, and has units of J/kg K. The universal gas constant has a value of 8314.3 J/mol K.

Read On ›
How do I decide whether to use 0.0821 or 8.314 for R? ›

The R's are actually the same just calculated with differnt units, typically you use R=0.0821 for PV=nRT but if you want J then you would use R=8.314. It's all about units.

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How do you find the universal gas constant? ›

For one mole, therefore, PV/T = R. The dimensions of the universal gas constant R are energy per degree per mole. In the metre-kilogram-second system, the value of R is 8.31446261815324 joules per kelvin (K) per mole. The universal gas constant is defined as Avogadro's number NA times the Boltzmann constant k.

Find Out More ›
What is the significance of the universal gas constant? ›

So, there must be a proportionality constant to obtain an equation. The proportionality constant is called the Universal gas constant (R). Physically, it relates the energy scale in physics to the temperature scale. Higher temperature means higher energy, and vice versa.

See More ›
How much is the universal gas constant? ›

R = 8.314462618... kg⋅m2⋅s−2⋅K−1⋅mol−1.

View More ›
Is 0.0821 always R? ›

The ideal gas constant, also known as the molar gas constant, is expressed as R within the formula for the ideal gas law, PV=nRT. The ideal gas constant is the same for all gases but can vary based on which units are being used, the most common expressions are R = 0.0821 (L • atm/ mol • K) OR R = 8.31 (J/ mol • K).

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What are the three values of universal gas constant? ›

Value of the Gas Constant
  • R = 0.0821 liter·atm/mol·K.
  • R = 8.3145 J/mol·K.
  • R = 8.2057 m3·atm/mol·K.
  • R = 62.3637 L·Torr/mol·K or L·mmHg/mol·K.

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Does the universal gas constant depend on PV nRT? ›

In a gas equation PV=nRT the value of universal gas constant depends upon the units of measurement. Its values are 8.314J/mol/K or 0.0821L. atm/mol/K or 2cal/mol/K.

View Details ›
What are the two gas constants? ›

Students are often confused by the units of the ideal gas constant. This confusion is compounded by the fact that there are two forms of the gas constant: the universal gas constant and the specific gas constant.

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What is the universal gas constant dependent on? ›

The value of the universal gas constant R depends on the units used for pressure, volume and temperature. Therefore, it depends on the units of measurement.

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What is the universal gas constant for air? ›

units as: R = 8.314 J/mol·K. This means that for air, you can use the value R = 287 J/kg·K. If you use this value of R, then technically the formula should be written as pV = mRT, where m represents the mass of air in kg (and we avoid having to do any calculations with moles.)

Know More ›
What is the unit of the universal gas constant? ›

The SI unit of the gas constant is joule per kelvin per mole. The value of the gas constant is. 3144598 J K - 1 m o l - 1 .

View Details ›
What is the universal gas constant unit? ›

Gas constant
Value of RUnit
SI units
8.31446261815324J⋅K−1⋅mol−1
8.31446261815324m3⋅Pa⋅K−1⋅mol−1
8.31446261815324kg⋅m2⋅s−2⋅K−1⋅mol−1
14 more rows

Continue Reading ›
What is the universal gas constant R kJ? ›

R is the gas constant, J/kgK or kJ/kgK and R = R /M where R is the Universal Gas Constant = 8.3144 kJ/kmole K M is the molecular weight, e.g. for air Mair = 28.96 kg/kmol, Rair = 0.2871 kJ/kgK. At moderate temperatures and pressures the properties internal energy and enthaply are assumed to be independent of pressure.

See Details ›
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