Activation Energy

The decomposition of NO2 follows a second order rate equation. Data at different temperatures are as follows:

T (K)		592	603	627	651.5	656
k (cm3/gmol.sec)  522	755	1700	4020	5030

Compute the energy of activation Energy from the data. The reaction is 2NO2 à 2NO + O2

Calculations:

Activation energy is found from the Arrhenius' relation

k = ko e-E/RT

i.e.,

ln k vs. 1/T is a straight line with a slope of -E/R

where, E is the activation energy; and

R is the universal gas constant.

T (K)

592

603

627

651.5

656

k (cm3/gmol.sec)

522

755

1700

4020

5030

1/T (oK-1)

0.001689

0.001658

0.001595

0.001535

0.001524

ln k

6.257668

6.626718

7.438384

8.299037

8.523175

From the above data, the following graph is drawn, and the slope is = -13622

Therefore,

E/R = 13622

E = 13622 x 8314 = 113253.3 kJ/kmol