Expansion of a gas in vacuum is called free expansion. Calculate the work done and the change in internal energy when 1 litre of ideal gas expands isothermally into vacuum until its total volume is 5 litre ?

Expansion of a gas in vacuum is called free expansion. Calculate the w

1.	Expansion of a gas in vacuum is called free expansion. Calculate the work done and the change in internal energy when 1 litre of ideal gas expands isothermally into vacuum until its total volume is 5 litre ?
Answer» Solution :Work DONE of a gas in vacuum, `W=-p_("ext") (V_(2) - V_(1) )` As `P_("ext" ) = 0` so, `W= -0(5-1) =0` As internal energy of an ideal gas depends only on temperature, therefore, for isothermal expansion of an ideal gas, internal energy remains constant, i.e., `Delta U=0` As `H= U + PV, Delta H = Delta U (U+ pV)= Delta U + pDelta V = Delta U + n R (Delta T)`. For isothermal process, `Delta T = 0 and` also `Delta U = 0`, as STATED above, therefore, `Delta H=0`.