Joule–Thomson coefficient and energy that must be supplied as heat to maintain constant temperature.

 Q. Given that µ = 0.25 K atm−1 for nitrogen, calculate the value of its isothermal Joule–Thomson coefficient. Calculate the energy that must be supplied as heat to maintain constant temperature when 15.0 mol N2 flows through a throttle in an isothermal Joule–Thomson experiment and the pressure drop is 75 atm.

Ans.  we know from the joule- Thomson Effect that

        

we have given, µ = 0.25 K atm−1

                         N2  = 15 mol

 

                         pressure drop is 75 atm.

finding Cp for N2 from equipartition of Energy = (5/2) R  or 20.785 J K^-1 mol^-1

to find the value of Energy to maintain constant Temperature, we know that dH/dp *n is the joule Thomson coefficient for the 1 mol gas 1mol gas means when gas flow through throttle its expand and cool so for maintaining T constant we need extra energy from external sources.

so, need of Energy is