## CH4 (g methane) + 2 O2 (g) → CO2 (g) + 2 H2O (ℓ)

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Combustion

## Stoichiometry

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 CH4            Mass: g O2             Mass: g or Gas Volume: L CO2            Mass: g or Gas Volume: L H2O            Mass: g Heat Released: kJ

## Enthalpy of Reaction

[1ΔHf(CO2 (g)) + 2ΔHf(H2O (ℓ))] - [1ΔHf(CH4 (g methane)) + 2ΔHf(O2 (g))]
[1(-393.51) + 2(-285.83)] - [1(-74.85) + 2(0)] = -890.32 kJ
-890.32 kJ     (exothermic)

## Entropy Change

[1ΔSf(CO2 (g)) + 2ΔSf(H2O (ℓ))] - [1ΔSf(CH4 (g methane)) + 2ΔSf(O2 (g))]
[1(213.68) + 2(69.91)] - [1(186.27) + 2(205.03)] = -242.83 J/K
-242.83 J/K     (decrease in entropy)

## Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(CO2 (g)) + 2ΔGf(H2O (ℓ))] - [1ΔGf(CH4 (g methane)) + 2ΔGf(O2 (g))]
[1(-394.38) + 2(-237.18)] - [1(-50.84) + 2(0)] = -817.9 kJ
-817.90 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-817.92 kJ     (spontaneous)

## Equilibrium Constant, K (at 298.15 K)

1.9854259928e+143
This process is favorable at 25°C.

## Reference(s):

Kotz, John C., Treichel, Paul, and Weaver, Gabriela. Chemistry & Chemical Reactivity 6th ed.; Thomson Brooks/Cole: Belmont, CA, 2006; p 162.