The kinetics of the catalytic decomposition of NH3 into N2 and H2 on a hot tungsten filament at 1100 °C was investigated by Kunsman. He measured the times (t1/2) required for half of NH3 to decompose at different initial NH3 pressures, as shown below:

Question

P (torr) t1/2 (minutes)
265 7.6
130 3.7
58 1.7
Determine (i) the order of the reaction and (ii) the rate constant.

Answer 1

a). NH3== N2 + H2
BAlance:

2NH3 == N2 + 3H2
-r= kC(NH3)2

>> Therefore th order of rxn is 2nd order