When placed in a large, closed, dry container at room temperature, the crystalline hydrate Na2SO4·10H2O spontaneously loses water:
Na2SO4·10H2O (s) → Na2SO4(s) + 10 H2O(g)
At room temperature, its ΔH° is positive. Does ΔS° for this reaction at room temperature change if the hydrated compound is added to a large, closed container that already has a large amount of water vapor present?