Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 12

# Account for the following : Ozone is thermodynamically unstable - Chemistry

Account for the following :

Ozone is thermodynamically unstable.

#### Solution

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.

Concept: P - Block Group 16 Elements - Ozone
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