Question

Consider the decomposition of no2. 2no2(g) → 2no(g) + o2(g) at 650 k, the rate constant is 1.66 sec-1. at 700k, the constant is 7.39 sec-1. calculate the activation energy.

Answer 1

Activation energy can be calculated using the formula:

$ln\frac{K_{1}}{K_{2}}=\frac{E_{a}}{8.314}[\frac{1}{T_{2}}-\frac{1}{T_{1}}]$  

At T₁=650 K, the rate constant, K₁ = 1.66 sec-1.  

At T₂=700 K, the constant, K₂ =7.39 sec-1.

Putting the values in the above equation,

$ln\frac{1.66}{7.39}=\frac{E_{a}}{8.314}[\frac{1}{700}-\frac{1}{650}]$  

Eₐ=1.12 ×10⁵ J mol⁻¹

or

Eₐ=112 KJ mol⁻¹