## B2O3 (s) + 3 Mg (s) → 2 B (s) + 3 MgO (s periclase)

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## Stoichiometry

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 B2O3           Mass: g Mg             Mass: g B              Mass: g MgO            Mass: g Heat Released: kJ

## Enthalpy of Reaction

[2ΔHf(B (s)) + 3ΔHf(MgO (s periclase))] - [1ΔHf(B2O3 (s)) + 3ΔHf(Mg (s))]
[2(0) + 3(-601.66)] - [1(-1272.77) + 3(0)] = -532.21 kJ
-532.21 kJ     (exothermic)

## Entropy Change

[2ΔSf(B (s)) + 3ΔSf(MgO (s periclase))] - [1ΔSf(B2O3 (s)) + 3ΔSf(Mg (s))]
[2(5.86) + 3(26.94)] - [1(53.97) + 3(32.69)] = -59.5 J/K
-59.50 J/K     (decrease in entropy)

## Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[2ΔGf(B (s)) + 3ΔGf(MgO (s periclase))] - [1ΔGf(B2O3 (s)) + 3ΔGf(Mg (s))]
[2(0) + 3(-569.02)] - [1(-1193.7) + 3(0)] = -513.36 kJ
-513.36 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-514.47 kJ     (spontaneous)

## Equilibrium Constant, K (at 298.15 K)

8.7455127211e+089
This process is favorable at 25°C.

## Reference(s):

Atkins, Jones, and Laverman. Chemical Principles 6th ed.; W.H. Freeman and Company: New York, NY, 2013; p F94.