Acetic acid was evaporated into a container of volume 21.45 cm3 at 437 K and at an external pressure of 764.3 Torr, and the container was then sealed. The mass of acid present in the sealed container was 0.0519 g. The experiment was repeated with the same container but at 471 K, and it was found that 0.0380 g of acetic acid was present. Calculate the equilibrium constant for the dimerization of acetic acid in the vapour and the enthalpy of vaporization. Use pϴ= 760 Torr, and assume that acetic acid is a perfect gas.