Two moles of an ideal gas kept at 300K expand isothermally and reversibly from an initial volume of 5.0L to a final volume of 10.0L.
(a) Calculate the change in entropy of the gas.
(b) Find the change in entropy of the surroundings during this reversible expansion.
(c) What is the total entropy change of the universe for this reversible expansion? Comment on your result.
(d) Suppose instead that the gas undergoes a free (sudden) expansion from 5.0L to 10.0L into vacuum, with no heat exchange with the surroundings. Determine the total entropy change of the universe in this case and state whether the free expansion is spontaneous, reversible or impossible.