The rate constant for the first-order reaction
N2O5 → 2 NO2 + 1/2 O2
is 3.19×10^-2 s^-1 at 45°C,
and the initial concentration
of N2O5 is 1.86×10^-3 M.
a. How long will it take for the concentration to decrease
to 5.00×10^-6 M?
b. How much longer will it take for a further decrease
to 4.00×10^-6 M?