Spontaneity in gas equations [ENDORSED]

[nelms6678]

If you're measuring spontaneity in the amount of moles of gas in an equation for example:
2 N2O(g)—> N2(g) + O2(g)

If the amount of moles are equal on both sides what does that tell about delta S?

[Chem_Mod]

Generally speaking, if the number of moles of gas increases in a reaction, this tends to increase the entropy. However, the only way to be sure is to calculate ΔS for the reaction.

If both sides have equal numbers of moles, then you must use another criterion to predict the sign of the entropy change for the reaction such as phase changes or molecular complexity. Again, the only way to be sure is to calculate ΔS for the reaction using standard molar entropies.