4 KO2 (s) + 2 H2O (ℓ) → 4 KOH (s) + 3 O2 (g)

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Stoichiometry

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Heat Added: kJ
KO2            Mass: g
H2O            Mass: g
KOH            Mass: g
O2             Mass: g  or Gas Volume: L

Enthalpy of Reaction

[4ΔHf(KOH (s)) + 3ΔHf(O2 (g))] - [4ΔHf(KO2 (s)) + 2ΔHf(H2O (ℓ))]
[4(-425.85) + 3(0)] - [4(-284.51) + 2(-285.83)] = 6.29999999999973 kJ
6.30 kJ     (endothermic)

Entropy Change

[4ΔSf(KOH (s)) + 3ΔSf(O2 (g))] - [4ΔSf(KO2 (s)) + 2ΔSf(H2O (ℓ))]
[4(78.87) + 3(205.03)] - [4(122.59) + 2(69.91)] = 300.39 J/K
300.39 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[4ΔGf(KOH (s)) + 3ΔGf(O2 (g))] - [4ΔGf(KO2 (s)) + 2ΔGf(H2O (ℓ))]
[4(-379.07) + 3(0)] - [4(-240.58) + 2(-237.18)] = -79.5999999999999 kJ
-79.60 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-83.26 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

8.8326825311e+013
This process is favorable at 25°C.

Reference(s):

Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; pp 135, 227.

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