Question

In a study of the gas phase decomposition of dinitrogen pentoxide at 335 K N2O3(g) 2 NO2(g) + % O2(g) the concentration of N,05 was followed as a function of time. It was found that a graph of In[N203) versus time in seconds gave a straight line with a slope of 6.25x10s and a y-intercept of -1.94 Based on this plot, the reaction is order in N205 and the rate constant for the reaction is

Answer 1

Part A) For the reaction,

N2O5 = 2NO2 + 1/2 O2

The plot of ln [N2O5] vs time (t) is a srraight line confirms the first order with respect to N2O5.

Thus,

For a first order reaction, the slope (m) = -K

Thus, rate constant (K) = - ( - 6.25 x 10^-3)

K = 6.25 x 10^-3 s-1

Therefore, options are:

First order

6.25 x 10^-3 s-1

Part B)

For the given reaction,

ln [H2O2] vs time give straight line, hence order is first.

Slope = - K = - (- 1.66 x 10^-3 min-1) = 1.66 x 10^-3 min-1

Hence,

Half life time = 0.6931 / 1.66 x 10^-3 min-1

= 0.4175 x 10^3 min

= 417.5 min