2 SO2 (g) + 1 O2 (g) → 2 SO3 (g)

Back to reactions list

 

Reaction Type:

Synthesis

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.

SO2            Mass: g  or Gas Volume: L
O2             Mass: g  or Gas Volume: L
SO3            Mass: g  or Gas Volume: L
Heat Released: kJ

Enthalpy of Reaction

[2ΔHf(SO3 (g))] - [2ΔHf(SO2 (g)) + 1ΔHf(O2 (g))]
[2(-395.72)] - [2(-296.83) + 1(0)] = -197.78 kJ
-197.78 kJ     (exothermic)

Entropy Change

[2ΔSf(SO3 (g))] - [2ΔSf(SO2 (g)) + 1ΔSf(O2 (g))]
[2(256.65)] - [2(248.11) + 1(205.03)] = -187.95 J/K
-187.95 J/K     (decrease in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[2ΔGf(SO3 (g))] - [2ΔGf(SO2 (g)) + 1ΔGf(O2 (g))]
[2(-371.08)] - [2(-300.19) + 1(0)] = -141.78 kJ
-141.78 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-141.74 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

6.9209141967e+024
This process is favorable at 25°C.

Reference(s):

Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 217.
Silberberg, Martin S. Chemistry: The molecular Nature of Matter and Change 4th ed.; McGraw-Hill: Boston, MA, 2006; p 127.
Atkins, Jones, and Laverman. Chemical Principles 6th ed.; W.H. Freeman and Company: New York, NY, 2013; p 428.

Back to list of reactions