B2H6 (g) + 6 H2O (ℓ) → 6 H2 (g) + 2 H3BO3 (s)

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Stoichiometry

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B2H6           Mass: g  or Gas Volume: L
H2O            Mass: g
H2             Mass: g  or Gas Volume: L
H3BO3          Mass: g

Enthalpy of Reaction

[6ΔHf(H2 (g)) + 2ΔHf(H3BO3 (s))] - [1ΔHf(B2H6 (g)) + 6ΔHf(H2O (ℓ))]
[6(0) + 2(-1094.33)] - [1(35.56) + 6(-285.83)] = -509.24 kJ
-509.24 kJ     (exothermic)

Entropy Change

[6ΔSf(H2 (g)) + 2ΔSf(H3BO3 (s))] - [1ΔSf(B2H6 (g)) + 6ΔSf(H2O (ℓ))]
[6(130.59) + 2(88.83)] - [1(232) + 6(69.91)] = 309.74 J/K
309.74 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[6ΔGf(H2 (g)) + 2ΔGf(H3BO3 (s))] - [1ΔGf(B2H6 (g)) + 6ΔGf(H2O (ℓ))]
[6(0) + 2(-969.01)] - [1(86.61) + 6(-237.18)] = -601.55 kJ
-601.55 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-601.59 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

2.4709532303416E+105
This process is favorable at 25°C.

Reference(s):

Jolly, William L. The Chemistry of the Non-Metals; Prentice-Hall: Englewood Cliffs, New Jersey, 1966; p 10.
Silberberg, Martin S. Chemistry: The molecular Nature of Matter and Change 4th ed.; McGraw-Hill: Boston, MA, 2006; p 128.

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