entropy sign

[itzeelpadillaDis1A]

How can we tell the sign of entropy based off a chemical equation?

[Julianna Thrasher 1B]

You can look at the phases of all substances in the chemical reaction. Entropy increases from solid --> liquid --> gas since entropy is a measure of disorder and disorder increases with with less rigidity of a substance. If the reactants are mainly liquids and solids and the products are all gases, then you know the entropy is increasing.

[Grace Han 2K]

gas>> liquid >> solid

If a rxn has only gas molecules, then you can subtract the number of moles from the product to the reactant. If it is negative, then the change in entropy is negative. If it is positive, then the change in entropy is positive for the forward reaction.

example
2CO(g) + O2(g) --> 2CO2(g)

2mol- (2mol- 1mol)= -1mol

This rxn has a negative change in entropy.

[Ishita Monga 1B]

If the mols of gas are increasing as a result of the reaction, entropy is +. If the mols of gas are decreasing, entropy is -.
If the reactants are changing from solid to liquid or liquid to gas, entropy is +. If they are changing from gas to liquid or liquid to solid, entropy is -.

[Veritas Kim 2L]

Do we have to indicate the signs of entropy?

[AtreyiMitra2L]

If there is net increase of gaseous moles --> increase in entropy. If there is a net decrease --> decrease in entropy. If appearence of aqueous, net increase. if we see an increase in molecular complexity with the products --> net increase.