## C3H8 (g propane) + 5 O2 (g) → 3 CO2 (g) + 4 H2O (g)

Back to reactions list

Combustion

## Stoichiometry

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.

 C3H8           Mass: g O2             Mass: g or Gas Volume: L CO2            Mass: g or Gas Volume: L H2O            Mass: g or Gas Volume: L Heat Released: kJ

## Enthalpy of Reaction

[3ΔHf(CO2 (g)) + 4ΔHf(H2O (g))] - [1ΔHf(C3H8 (g propane)) + 5ΔHf(O2 (g))]
[3(-393.51) + 4(-241.82)] - [1(-103.85) + 5(0)] = -2043.96 kJ
-2,043.96 kJ     (exothermic)

## Entropy Change

[3ΔSf(CO2 (g)) + 4ΔSf(H2O (g))] - [1ΔSf(C3H8 (g propane)) + 5ΔSf(O2 (g))]
[3(213.68) + 4(188.72)] - [1(270.2) + 5(205.03)] = 100.57 J/K
100.57 J/K     (increase in entropy)

## Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[3ΔGf(CO2 (g)) + 4ΔGf(H2O (g))] - [1ΔGf(C3H8 (g propane)) + 5ΔGf(O2 (g))]
[3(-394.38) + 4(-228.59)] - [1(-23.56) + 5(0)] = -2073.94 kJ
-2,073.94 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-2073.94 kJ     (spontaneous)

## Equilibrium Constant, K (at 298.15 K)

approaches infinity
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 146.