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Gas Constant

The gas constant is a physical constant denoted by R and is expressed in terms of units of energy per temperature increment per mole. It is also known as the ideal gas constant or molar gas constant or universal gas constant. The gas constant value is equivalent to the Boltzmann constant but expressed as the pressure-volume product instead of energy per increment of temperature per particle.

Gas Constant Value

In physics, the gas constant is the proportionality constant used to relate the energy scale to the temperature scale, when one mole of particles at a defined temperature is considered. The ideal gas constant is the combination of Boyle’s law, Avogadro’s number, Charles’s law and Gay-Lussac’s law. Thus, the gas constant R can be given as –

Gas constant R = 8.3144598(48) J⋅mol−1⋅K−1

The digits inside the parentheses are the uncertainty in the measurement of the gas constant value.

Read More: Boltzmann Constant

Gas Constant in Different Units

The gas constant is inversely used in diverse disciplines. Hence, it is expressed in many units. Some gas constant values in different units are listed below-

Gas Constant Value Units
8.3144598(48) J⋅K−1⋅mol−1
8.3144598(48)×103 amu.m2.s-2.K-1
8.3144598(48) m3.Pa.K-1.mol-1
62.363577(36) L.Torr.K-1.mol-1
1.9872036(11)×10−3 kcal.K-1.mol-1
8.2057338(47)×10−5 m3.atm.K-1.mol-1
0.082057338(47) L.atm.K-1.mol-1

R Constant for Atm

In the US Standard Atmosphere the R constant for atm is given as

R = 8.31432×103 N⋅m⋅kmol−1⋅K−1.

Read More: R Constant

Specific Gas Constant

The ratio of the molar gas constant(R) to the molar mass(M) of the gas mixture is called The specific gas constant. Denoted by Rspecific and mathematically expressed as –

\(\begin{array}{l}R_{specific}= \frac{R}{M}\end{array} \)


Using the ideal gas equation PV = n RT. The gas constant R can be expressed as-

\(\begin{array}{l}R=\frac{PV}{nT}\end{array} \)


  • P is the pressure.
  • V is the volume,
  • n is the number of moles of the given substance
  • T is the temperature.

Thus, writing pressure as force per unit area we can derive the dimensional expression for R as-

\(\begin{array}{l}R=\frac{\left ( \frac{force}{area} \right )\times volume}{amount\;\times temperature}\end{array} \)

Area and Volume can be expressed in terms of length as volume=(length)3 and area = (length)2

Thus we get-

\(\begin{array}{l}R=\frac{\left ( \frac{force}{length^{2}} \right )\times \left ( length \right )^{3}}{amount\;\times temperature}=\frac{force\;\times\; length}{amount\;\times \;temperature}\end{array} \)

Since force times length is work we get-

\(\begin{array}{l}R=\frac{work}{amount\;\times \;temperature}\end{array} \)

Thus gas constant can be interpreted as work per degree per mole.

Hope you have understood what is gas constant. the gas constant value in different units along with the ideal gas formula and Application in physics.

Physics Related Topics:

To know more about Boyle’s law, click on the video below

Frequently Asked Questions – FAQs

What is the formula to calculate the specific gas constant?

Specific gas constant is given by the formula:
\(\begin{array}{l}R_{specific}=\frac{R}{M}\end{array} \)

What is the value of Gas constant (R)?

The value of Gas constant is R = 8.3144598(48) J⋅mol−1⋅K−1

Write the formula for an ideal gas equation.

The ideal gas equation is given by PV=nRT.

What is a gas constant also known as?

Gas constant is also known as ideal gas constant or molar gas constant or universal gas constant.

The ideal gas constant is the combination of which laws?

The ideal gas constant is the combination of:
  • Boyle’s law
  • Charles’s Law
  • Gay-Lussac’s law
  • Avogadro’s number

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