Question

Consider the listed gases at 298K. Which of these gases will cool upon expansion? Which of these gases will warm upon expansion? Justify answers using bulk and molecular physical properties of the gases.

N2, CO2, He, CH4, H2

Answer 1

1. At 298 k the N2,CH4,CO2 gases will cool upon expansion because of their inversion temperatures are more than 298k so when pressure starts decreasing as per the joule thompson curve during expansion the temperature decreases gradually so.

2. In case of H2,He the inversion temperatures are 51K around so gases will not get cooled while expansion ,during the expansion the intermolecular energy is high compared to the forces applying on the gases so gases may get warmed.

check the joule thompson effect for the more clarification. check the following T vs P plot it has the inversioncurve