A tank containing carbon dioxide at 400K and 50 bar is vented until the temperature in the tank falls to 300K. Assuming there is no heat transfer between the gas and the tank, find the pressure in the tank at the end of the venting process and the fraction of the initial mass of gas remaining in the tank for each of the following cases. a) the equation of state of carbon dioxide is P(V_mol-b)=R*T. b) Carbon dioxide obeys the law of corresponding states. c) Carbon dioxide obeys the Peng-Robinson equation of state.