Given, half-life = 69.3 s Half-life for first order reaction k=
0.693
t1∕2
=
0.693
69.3
=10−2s−1 For first order kinetics, k=
2303
t
log
[R]0
[R]t
10−2=
2.303
230
log
0.4
pt
log
0.4
pt
=1 log10=log
0.4
pt
(as log 10 = 1) 10=
0.4
pt
pt=
0.4
10
=0.04 From the reaction, A(g) → P(g) + Q(g) + R(g) At t=0 0.4 0 0 0 At t=230s 0.04 0.4 - x 0.4-x 0.4-x Now, at time t = 230 s, the pressure of the gases