A 2.00 L flask originally contains 1.00 g of ethane, C_2H_6, and 3.20 g of oxygen at 21 degree C. Upon ignition, the ethane reacts completely with the oxygen (there are no reactants remaining) to produce CO_2 and water vapor, and the temperature increases to 200 degree C. Determine the total pressure and the partial pressure of each gas before and after the reaction.