One mole of an ideal gas at 300K is slowly compressed isothermally and reversibly from an initial volume of 4.0L to a final volume of 1.0L. Take R=8.314J mol−1K−1.
(a) Calculate the mechanical work done on the gas during the compression.
(b) Express the result in (i) joules and (ii) litre-atmosphere to three significant figures.
(c) State whether the numerical value obtained in part (a) would be larger, smaller, or equal if the same compression were carried out irreversibly at constant external pressure equal to the final equilibrium pressure. Justify your answer qualitatively.