1.2 The molar energy of a monatomic gas which obeys van der Waals’ equation is given by where V is the molar volume at temperature T, and a is a constant. Initially one mole of the gas is at the temperature T1 and occupies a volume V1. The gas is allowed to expand adiabatically into a vacuum so that it occupies a total volume V2. What is the final temperature of the gas?