First order decay processes as described in the previous problem can also be
applied to a variety of atomic and molecular processes. For example, in
aqueous solution the decay of singlet molecular oxygen
\(\left(\mathrm{O}_{2}\left(^{1} \Delta_{g}\right)\right)\) to the groundstate
triplet configuration proceeds according to
$$\frac{\left[\mathrm{O}_{2}\left(^{1}
\Delta_{g}\right)\right]}{\left[\mathrm{O}_{2}\left(^{1}
\Delta_{g}\right)\right]_{0}}=e^{-\left(2.4 \times 10^{5}
\mathrm{s}^{-1}\right) t}$$ In this expression,
\(\left[\mathrm{O}_{2}\left(^{1} \Delta_{g}\right)\right]\) is the concentration
of singlet oxygen at a given time, and the subscript "0" indicates that this
is the concentration of singlet oxygen present at the beginning of the decay
process corresponding to \(t=0\).
a. How long does one have to wait until \(90 \%\) of the singlet oxygen has
decayed?
b. How much singlet oxygen remains after \(t=\left(2.4 \times 10^{5}
s^{-1}\right)^{-1} ?\)