Quick entropy definition question

[jiejsun]

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I understand entropy changes when there's phase change involved (e.g. Liquid -> gas)

What about if there's change number of moles of substance after rxn(in same gas phase) ? Like in this following case, can I say the system decrease in entropy? Coefficients went down from 2 to 1

NO(g) + O2 (g) --> NO2(g)

 

[ijk90825]

When the mole decreases entropy is -, mole increases entropy is +.
Think like this, if there are more gas, there's bigger disorder so the entropy is higher.
Solid and liquid doesn't count in moles