Chem
posted by Bryan .
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 at 485degreesC.
If a 2.5L reaction vessel initially contains 724 torr of cyclopropane at 485degreesC, how long will it take for the partial pressure of cylclopropane to drop to below 104 torr? Express answer in minutes

I think you can use partial pressure the same way as grams, concn, etc; therefore,
ln(No/N) = kt
You know No = 724 torr
N = 104 torr
k = from the problem.
Solve for t and convert to minutes. You did not post units for k. Take your queue form the units of k for the kind of conversion you need.