Q. 255.0( 2 Votes )

# Value of universal gas constant (R) is same for all gases. What is its physical significance?

Answer :

The universal gas constant;

Its unit is obtained from expression, R=

Pressure = = =

Volume = length^{3}

So, ==

Thus, unit of R is energy per mole per Kelvin. R is the amount of

Work (energy) obtained from per mole of gas when its temperature raised by 1 kelvin.

Unit R depends on units of P, V and T. If pressure is measured in Pascal, per

Mole volume is measured in m^{3} and temperature is measured in Kelvin then

Unit of ‘R’ are in Pa m^{3}K^{-1}mol^{-1} or JK^{-1}mol^{-1}. Joule is the unit of work done so

‘R’ is work done per Kelvin per mole. For 1 mole gas

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 8.3144598 joules per Kelvin per mole.

Hence R only depends on unit of different parameter P, V, n, T. So R values same for all gases.

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