Question

The experimental data for decomposition of N₂O₅ [2N₂O₅ → 4NO₂ + O₂] in gas phase at 318 K are given below:

Time/s1O2 x[N2 O5 ]/molL-1	0 1.63	400 1.63	800 1.14	1200 0.93	1600 0.78
Time/s102x[N2O5]/ molL-1	2000 0.64	2400 0.53	2800 0.43	3200 0.35

(i) Plot (N₂O₅) aganist t.
(ii) Find the half life period for the reaction.
(iii) Draw a graph between log (N₂O₅) and t.
(iv) What is the rate law ?
(v) Calculate the rate constant.
(vi) Calculate the half life period from k and compare it with answer (ii).

Answer 1

(i) Plot (N₂O₃) aganist t

(ii) Half life period (t_1/2) for the given reaction is the time during which initial concentration of N₂O₅ changes from 1.63 x 10^-2 M to half this value i.e. to 0.815 x 10^-2 M and in the graph it has been shown to be 1440 s.

(iii) Graph between log [N₂O₅] and time t.

(iv) Since a straight line is observed when log [N₂O₅] is plotted against time, therefore the reaction is of first order.