Question

When helium gas is allowed to expand into vacuum, heating effect is observed. The reason for this is:

(Assume $He$ as a non-ideal gas)

• A. $He$ is an inert gas
• B. the inversion temperature of Helium is very high
• C. the inversion temperature of Helium is very low
• D. $He$ has the lowest boiling point

Answer 1

Answer: (C)

the inversion temperature of Helium is very low

Helium is assumed as a non-ideal gas.
When helium gas is allowed to expand into vacuum, the heating effect is observed.
This is because the inversion temperature of Helium is very low.

Hydrogen and Helium exhibit heating effect during Joule-Thomson expansion due to low inversion temperature. Other gases exhibit cooling effect during Joule-Thomson expansion as work of expansion (during adiabatic expansion) is done at the cost of internal energy.