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Problem 1 - Entrance Test

Calculate the entropy change for the reaction: 2 SO₂(g) + O₂(g) → 2 SO₃(g) Given: S°(SO₂) = 248 J/mol·K, S°(O₂) = 205 J/mol·K, S°(SO₃) = 256 J/mol·K.

Correct: A

ΔS° = [2×S°(SO₃)] − [2×S°(SO₂) + S°(O₂)] = (512) − (496 + 205) = −189 J/K. Closest option is -198 J/K.