If 1.00 atm of N2O5 is introduced into an evacuated 5.00L flask, what will be the total pressure of the gases in the flask after 1.5 hours? At a particular temperature the first-order gas-phase reaction 2N2O5→ 2N2O4 +O2 has a half-life for the disappearance of dinitrogen pentoxide of 3240s.