Define Entropy

[ClaireHW]

What is entropy? Physically what does an entropy change look like?

(Claire Woolson Dis 1K)

[ClaireHW]

Can someone also do the same for Gibbs Free Energy?

Thanks!

(Claire Woolson Dis 1K)

[Vincent Tse 1K]

Entropy is a thermodynamic quantity denoted by ΔS, and refers to the "disorder" (an potentially confusing term, if you remember from lecture) of something. In essence, most reactions tend to favor going from low entropy to high entropy (you won't need to put in work). A physical example would be a phase change from solid to liquid.


Gibbs free energy is basically the free energy in a process available to do work. An important relationship to consider is ΔG = ΔH - TΔS, which, if you know the signs of the unknowns, you can determine the sign of ΔG and hence predict if a reaction is favorable or not.

[Liz White 1K]

In summary, entropy is equal to the amount of disorder. Gibbs Free Energy is equal to the enthalpy minus the entropy times the temperature. We can use Gibbs Free Energy to determine whether or not a reaction is spontaneous, as a negative value of G will show spontaneity.

[Helen Shi 1J]

Can someone explain why we divide q by temperature?