Consider a rigid tank with a partition such that there are two equal volumes which are known. On one side has water at a given temperature and pressure and known mass. The other side is a vacuum. If the partition is removed, and the tank is perfectly insulated, can the final equilibrium state be determined? How many independent properties are needed to fix a state? What is the first law for the process described above? Remember we are only interested in the initial and final equilibrium states, not the violent activity that takes place when the partition is removed. Explain you ranswer.