2 H3PO4 (aq) + 3 Na2SO3 (s) → 2 Na3PO4 (aq) + 3 H2O (ℓ) + 3 SO2 (g)

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Reaction Type:

Double Displacement/Decomposition of a Sulfite

Stoichiometry

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Heat Added: kJ
H3PO4          Mass: g  or Solution Volume: mL of Concentration: mol/L
Na2SO3         Mass: g
Na3PO4         Mass: g
H2O            Mass: g
SO2            Mass: g  or Gas Volume: L

Enthalpy of Reaction

[2ΔHf(Na3PO4 (aq)) + 3ΔHf(H2O (ℓ)) + 3ΔHf(SO2 (g))] - [2ΔHf(H3PO4 (aq)) + 3ΔHf(Na2SO3 (s))]
[2(-1997.68) + 3(-285.83) + 3(-296.83)] - [2(-1277.38) + 3(-1090.35)] = 82.4699999999993 kJ
82.47 kJ     (endothermic)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[2ΔGf(Na3PO4 (aq)) + 3ΔGf(H2O (ℓ)) + 3ΔGf(SO2 (g))] - [2ΔGf(H3PO4 (aq)) + 3ΔGf(Na2SO3 (s))]
[2(-1804.5) + 3(-237.18) + 3(-300.19)] - [2(-1018.8) + 3(-1002.07)] = -177.3 kJ
-177.30 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-176.92 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

1.157029665e+031
This process is favorable at 25°C.