Sr3(AsO4)2 (s) → 3 Sr+2 (aq) + 2 AsO4-3 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[3ΔHf(Sr+2 (aq)) + 2ΔHf(AsO4-3 (aq))] - [1ΔHf(Sr3(AsO4)2 (s))]
[3(-545.8) + 2(-888.1)] - [1(-3317.08)] = -96.52 kJ
-96.52 kJ     (exothermic)

Entropy Change

[3ΔSf(Sr+2 (aq)) + 2ΔSf(AsO4-3 (aq))] - [1ΔSf(Sr3(AsO4)2 (s))]
[3(-32.6) + 2(-162.8)] - [1(255.22)] = -678.62 J/K
-678.62 J/K     (decrease in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[3ΔGf(Sr+2 (aq)) + 2ΔGf(AsO4-3 (aq))] - [1ΔGf(Sr3(AsO4)2 (s))]
[3(-559.5) + 2(-648.4)] - [1(-3080.26)] = 104.96 kJ
104.96 kJ     (nonspontaneous)

From ΔG = ΔH - TΔS:
105.81 kJ     (nonspontaneous)

Equilibrium Constant, K (at 298.15 K)

4.08112956851658E-19
This process is not favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (4.08112956851658E-19) will be used to calculate the equilibrium concentration for all species.

Sr3(AsO4)2 Sr+2 AsO4-3
Initial M   0 0
Change -x +3x +2x
Equilibrium