## 2 H3PO4 (aq) + 3 MgCO3 (s) → Mg3(PO4)2 (s) + 3 H2O (ℓ) + 3 CO2 (g)

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## Reaction Type:

Double Displacement/Decomposition of a Carbonate

## Stoichiometry

Enter a mass or volume in one of the boxes below. Upon hitting submit, the stoichiometric equivalents will be calculated for the remaining reactants and products. All gases are assumed to be at STP.

 Heat Added: kJ H3PO4          Mass: g or Solution Volume: mL of Concentration: mol/L MgCO3          Mass: g Mg3(PO4)2      Mass: g H2O            Mass: g CO2            Mass: g or Gas Volume: L

## Enthalpy of Reaction

[1ΔHf(Mg3(PO4)2 (s)) + 3ΔHf(H2O (ℓ)) + 3ΔHf(CO2 (g))] - [2ΔHf(H3PO4 (aq)) + 3ΔHf(MgCO3 (s))]
[1(-3780.66) + 3(-285.83) + 3(-393.51)] - [2(-1277.38) + 3(-1095.79)] = 23.4500000000007 kJ
23.45 kJ     (endothermic)

## Entropy Change

[1ΔSf(Mg3(PO4)2 (s)) + 3ΔSf(H2O (ℓ)) + 3ΔSf(CO2 (g))] - [2ΔSf(H3PO4 (aq)) + 3ΔSf(MgCO3 (s))]
[1(189.2) + 3(69.91) + 3(213.68)] - [2(-221.75) + 3(65.69)] = 1286.4 J/K
1,286.40 J/K     (increase in entropy)

## Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(Mg3(PO4)2 (s)) + 3ΔGf(H2O (ℓ)) + 3ΔGf(CO2 (g))] - [2ΔGf(H3PO4 (aq)) + 3ΔGf(MgCO3 (s))]
[1(-3538.83) + 3(-237.18) + 3(-394.38)] - [2(-1018.8) + 3(-1012.11)] = -359.58 kJ
-359.58 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-360.09 kJ     (spontaneous)

## Equilibrium Constant, K (at 298.15 K)

9.9814994582e+062
This process is favorable at 25°C.