Question

A well insulated tank is initially divided in half by an impermeable membrane. In one half of the tank is an ideal gas at P = 1 atm and T = 200°C; in the other is nothing, just vacuum. You hear aloud pop and find that the membrane has ruptured letting the ideal gas fill the entire thing. What is Asuni, the molar change in entropy for the universe from before the rupture to a long time after?

Fig: 1