1 mol of water vapour triples its initial volume of 1L reversibly at 25 C. (a) Calculate the work done by the vapour, assuming that it is an ideal gas. Provide an analytical expression as well as a numerical answer. [7] Calculate the work done by the vapour, assuming that it obeys the van der Waals equation, with a = 553.6LZkPa/mol and b = 0.3049 L mol-. Provide an analytical expression as well as a numerical answer. [12] Repeat (a) and (b), assuming that the initial volume is 5 L. In which case is the idea-gas approximation more accurate? Explain why. [6] (6) (c)