3) A mixture of nitrogen and oxygen (xN2=0.7) behaves as an ideal gas mixture. 50 moles of this mixture at 1 bar and 25 °C are fed into an initially-empty, rigid, diathermal vessel causing the pressure in the vessel to reach 1 bar. Assuming the surroundings are also at 25 °C, calculate the heat transfer needed for the gas mixture in the vessel to be at 25 °C. At this temperature, Cp for nitrogen = 1.040 J/(g K) and Cp for oxygen = 0.918 J/(g K).