Page 78 - Basic physical chemistry for the atmospheric sciences

64 Basic physical chemistry
important than N202(g) during the reaction, which estab­
lishes that the first mechanism is more important than the
second. ]
3 . 1 4. The elementary reaction

which is a possible source of cloud-water nitrate, occurs in
a single step. If the rate coefficients for the forward and
1 2 and 5 . 0 x 1 0 - 2
reverse reactions are l . 5 x 10 - M - 1 s - 1 ,
respective y , what is the equilibrium constant for the re­
l
action?
3 . 1 5 . The overall reaction fo r nitramide (02NNH2) ( a possible
constituent of secondary particles formed by urban air pol­
lution) decomposing in solution is

The rate law determined experimentally is
d[N20(aq)] [02NNH2(aq)]
k
dt [H+ (aq)]
Some proposed reaction mechanisms are

k 1 r
02NNH2(aq) � N20(aq) + H20(aq) (slow) (i)
k 1 r

kzr
02NNHz(aq) + H + (aq) � 02NNH{ (aq) (fast equilibrium)
k2r (ii)
k)f
02NNH3+ (aq) � N20(aq) + H o + (aq) (slow)
3
k3r
k4r
02NNHz(aq) � 02NNH -(aq) + H + (aq) (fast equilibrium)
k4r
ksr
02NNH - (aq) � N20(aq) + OH -(aq) (slow) (iii)
ksr
k6f
H + (aq) + o H - (aq) � H20(aq) (fast)
k6r
(a) Which of the reaction mechanisms is consistent with the
rate law?