Question:
Expansion of gas in a vacuum is called free expansion. Calculate the work is done and the change in internal energy when 1 litre of an ideal gas expands isothermally into a vacuum until its total volume is 5 litre?
Solution:
Work done in vacuum is calculated by :
-w = Text (Vinitial – Vfinal )
Pext= 0
–w = 0x(5-1) = 0.
For isothermal expansion q=o
q= ∆U + (-w)
Hence ∆U will be 0.