A composite isolated system consists of one mole of a monatomic ideal gas and two moles of a diatomic ideal gas, in a container of total volume V, but separated into two subsystems of equal volume V/2 by a fixed impermeable, diathermal wall.
The wall separating the two systems is now released and allowed to move, allowing the systems to reach a new equilibrium. Calculate the final volume of each gas, and the change in total entropy.