Question

Account for the following :

Ozone is thermodynamically unstable.

Answer 1

Ozone decomposes into O₂ with the evolution of heat, i.e. ΔH is negative (exothermic).

`O_3->O_2+O" "DeltaH="negative"`

Since the decomposition of O₃ increases the number and freedom of particles, entropy also increases.

`therefore DeltaS="positive"`

Now, ΔG = ΔH − TΔS

Both −∆H  and`-TDeltaS` (since ∆S is positive) result into large negative ∆G. Hence, O₃ becomes thermodynamically unstable and decomposes into oxygen easily.