Cyclopropane (C3H6) reacts to form propene (C3H6) in the gas phase. The reaction is first order in cylclopropane and has a rate constant of 5.87*10^-4/s at 485 C.
If a 2.1-L reaction vessel initially contains 722 torr of cyclopropane at 485 C, how long will it take for the partial pressure of cylclopropane to drop to below 105 torr?