Question

Calculate the standard entropy change for the reaction: 2SO3(g) + O2(g) → 2SO4(g) Given the following standard entropies of formation: ΔS°f SO3(g) = 256.2 J/K mol ΔS°f O2(g) = 205.0 J/K mol ΔS°f SO4(g) = 296.8 J/K mol

Answer 1

To calculate the standard entropy change  S  for the reaction, we can use the following equation:S = nSf products  - nSf reactants where n is the stoichiometric coefficient of each species in the balanced chemical equation.For the given reaction:2SO3 g  + O2 g   2SO4 g We can plug in the given standard entropies of formation  Sf  for each species:S = [2  Sf SO4  -  2  Sf SO3  + Sf O2  ]Now, substitute the given values:S = [2  296.8 J/K mol -  2  256.2 J/K mol + 205.0 J/K mol ]S = [593.6 J/K mol -  512.4 J/K mol + 205.0 J/K mol ]S = 593.6 J/K mol - 717.4 J/K molS = -123.8 J/K molThe standard entropy change for the reaction is -123.8 J/K mol.