Question

Consider a generic element A. It exists in the gas phase as a triatomic molecule A₃ or as a diatomic molecule A₂.

Calculate ΔS^o in J/K for the reaction: 2A₃ → 3A₂ using the following values

S^o = 207.9 J/(mol.K) for A₂(g) and 236.5 J/(mol.K) for A₃(g) at 25 ^oC.

Answer 1

given reaction is 2A₃  $\rightarrow$ 3A₂

S⁰ A₃= 236.5J/K

S⁰ A₂= 207.9 J/K

S⁰ = S⁰ (Product) - S⁰ (Reactant)

S⁰ = [(3 S⁰ A₂)] - [(2X S⁰ A₃)] substitute above values in this formula

= [  (3207.9 )] - [(2x236.5)]

= [623.7] - [473] = 150.7

ans S⁰ = 150.7 J/K for given reaction