A process requires a mixture that is 21 percent oxygen, 78 percent nitrogen, and 1 percent argon by volume. All three gases are supplied from separate tanks to an adiabatic, constant-pressure mixing chamber at 200 kPa but at different temperatures. The oxygen enters at 10oC, the nitrogen at 60oC, and the argon at 200oC. Determine the total entropy change for the mixing process per unit mass of mixture.