 # What is the value of R (Universal gas constant) in SI unit?

R = 8.3145J/mol.K

### Value of R-Universal gas constant

The ideal gas law states that the product of the pressure and the volume of one gram molecule of an ideal gas is equal to the product of the absolute temperature of the gas and the universal gas constant.

The empirical form of ideal gas law is given by:

PV=nRT

where

P = pressure,

V = volume,

n = number of moles

T = temperature.

R is known as the universal gas constant =8.3145J/mol. K. The value of the gas constant ′R′ depends on the units used for pressure, volume and temperature.

• When we use the gas constant R = 8.31 J/K.mol, then we have to plug in the pressure P in the units of pascals Pa, volume in the units of m3 and the temperature T in the units of kelvin K.
• When we use the gas constant R = 0.082 L.atm/K.mol then pressure should be in the units of atmospheres atm, volume in the units of litres L and the temperature T in the units of kelvin K. (14) (7)