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.
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)
[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)
This process is favorable at 25°C.
Atkins, Jones, and Laverman. Chemical Principles 6th ed.; W.H. Freeman and Company: New York, NY, 2013; p F94.