## 2 Na2O2 (s) + 2 H2O (ℓ) → 4 NaOH (aq) + O2 (g)

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## Stoichiometry

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 Na2O2          Mass: g H2O            Mass: g NaOH           Mass: g O2             Mass: g or Gas Volume: L Heat Released: kJ

## Enthalpy of Reaction

[4ΔHf(NaOH (aq)) + 1ΔHf(O2 (g))] - [2ΔHf(Na2O2 (s)) + 2ΔHf(H2O (ℓ))]
[4(-470.09) + 1(0)] - [2(-513.38) + 2(-285.83)] = -281.94 kJ
-281.94 kJ     (exothermic)

## Entropy Change

[4ΔSf(NaOH (aq)) + 1ΔSf(O2 (g))] - [2ΔSf(Na2O2 (s)) + 2ΔSf(H2O (ℓ))]
[4(48.25) + 1(205.03)] - [2(94.81) + 2(69.91)] = 68.59 J/K
68.59 J/K     (increase in entropy)

## Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[4ΔGf(NaOH (aq)) + 1ΔGf(O2 (g))] - [2ΔGf(Na2O2 (s)) + 2ΔGf(H2O (ℓ))]
[4(-419.18) + 1(0)] - [2(-449.78) + 2(-237.18)] = -302.8 kJ
-302.80 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-302.39 kJ     (spontaneous)

## Equilibrium Constant, K (at 298.15 K)

1.1251661393e+053
This process is favorable at 25°C.

## Reference(s):

Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 184.