Which is the best explanation for the negative sign of ∆Sº in the following reaction? CaSO4(s) → Ca2+(aq) + SO42–(aq) ∆Sº = –143 J mol–1 K–1 | Thermodynamics

Question

Which is the best explanation for the negative sign of ∆Sº in the following reaction?
CaSO₄(s) → Ca²⁺(aq) + SO₄₂–(aq)
∆Sº = –143 J mol–1 K–1

There are more ways of arranging the Ca²⁺ and SO₄₂– ions in aqueous solution than in the crystal lattice.

Solid CaSO₄ is a network covalent solid, whereas it separates into ions in aqueous solution.

Aqueous Ca²⁺ and SO₄₂– ions are tightly solvated, decreasing the number of ways of arranging water molecules when the solid dissolves.

✓ Correct

Calcium sulfate dissolves exothermically, leading to a net loss of entropy.

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