As shown in Fig. 21-2, a container is separated into two equal-volume compartments. The two compartments contain equal masses of the same gas, 0.740 g in each, and cv for the gas is 745 J/kg·K. At the start, the hot gas is at 67.0 °C, while the cold gas is at 20.0 °C. No heat can leave or enter the compartments except slowly through the partition AB. Find the entropy change of each compartment as the hot gas cools from 67.0 °C to 65.0 °C.