Entropy??

[Jules7890]

I read about the second law of thermodynamics just yesterday, and I HATE the concept of entropy. My textbook says that entropy is the disordered energy (or heat, right? does it only include heat?) in a system.

 

It gave me this formula:

 

G = H - TS

 

which is supposed to mean:

 

Free energy = Total energy - (Temperature in K)(Entropy)

 

But how would a scientist quantitatively measure entropy to use this equation? Or is the equation just a way of explaining the concept and not meant to be used?

 

Anyways, what really pisses me off is the fact that they describe "entropy" as "disorder" or "randomness", when I always thought scientists would know better than to use words like that. Isn't the study of science based on the concept that nothing is random? Heat energy is just another form of kinetic energy, and it's governed by the same strict physical laws as everything else, so what makes it so "random"?

And has anyone ever tried to harness that energy? I bet it would be possible.

[antimatter]

Entropy is just disorder in the Universe caused by motion (Heat!).

I don't see the problem.

 

 

Isn't the study of science based on the concept that nothing is random?

 

What about Quantum Mechanics...

[Jules7890]

Oh yeah. ..... I don't know much about quantum mechanics, but I know what you're getting at.

 

I guess the particles' motion in hot matter is kind of random and doesn't have a direction, so that makes sense now that I think harder about it ... but the heat is still governed by physical laws. Saying that heat is random just because the particles vibrate somewhat randomly is like saying that the chemical energy in atoms is random because the electrons move randomly. And that pretty much covers all energy, doesn't it?

 

Plus, the concept that entropy is continuously growing means that heat energy is impossible to convert, which I find hard to believe.

[Mr Skeptic]

Entropy also includes things like mixing different chemicals together, even if there is no change in heat. Remember also that heat cannot be used for energy directly, but must have a heat difference to use it. Entropy encompasses lots of things, and chaos and disorder are very good descriptions of it.

[DJBruce]

Just remember the motion of most of the particles entropy deals with is random. Plus physics does no strive to give order to the universe but it tries to understand the chaos we live in.

 

I think there where a few errors in your equation. I'm not sure if you new that or not.

 

[math]\Delta G=\Delta H-(T)(\Delta S_{int})[/math]

 

Where

[math]\Delta H=\sum H^{0}_{F}(products)-\sum H^{0}_{F}(reactants)[/math]

 

[math]\Delta S=\sum S^{0}(products)-\sum S^{0}(reactants)[/math]

and T is measured in Kelvin

 

[math]\Delta G<0[/math] Spontaneous

[math]\Delta G=0[/math] Neither reactions happens has equilibrium

[math]\Delta G>0[/math] Non spontaneous

[swansont]

Plus, the concept that entropy is continuously growing means that heat energy is impossible to convert, which I find hard to believe.

 

Surely you've learned that you can't convert heat into work with 100% efficiency. That's where entropy comes into play.