# Why is entropy important?

1. Aug 31, 2010

### samblohm

Why is it important? I know it is a measure of the disorder of the system and the amount of possible outcomes. If it always increases, why should any chemist care about it?

2. Aug 31, 2010

### alxm

Why does ammonium chloride dissolve in water?
Why is rubber elastic?

3. Aug 31, 2010

### samblohm

I assume because of its entropy. Could you explain?

4. Sep 1, 2010

### alxm

I could explain, but I don't see why I should. Every general/introductory chemistry textbook covers the basics of entropy in chemistry.
So if you're asking this question, you haven't made an effort to find out on your own. In which case I'm disinclined to help.

Please read up on the subject, then come back and ask if you don't understand something. But don't ask for a private lesson.

5. Sep 1, 2010

### iratern

Well IMO, entropy is just a abstraction of what's actually going on. I mean entropy is a macro property based on a substances micro-properties. Now if you have a gas in a container and you only have 2 gas molecules then you wouldn't need entropy. You can do all the calculations you want just using by analyzing the interaction of the 2 molecules (Of course in an ideal container).

But what about when you have 1million? Anyone can easily see that doing such calculations is almost (if not actually) impossible (Since, technically, using classical physics we could calculate every single position the molecules would assume. But that would require a vast computational power beyond our ability). So why bother when you can use entropy, to approximate it? (I couldn't find a better word than approximate)

Now since I believe that what alxm said is true I will refrain from telling you too much until you have a better idea of what entropy actually is.

(Hint: what happens when you flip a coin? you could calculate the side that will come up, but instead you say that there's a 50-50 probability of heads or tails. Think a bit now....)

Disclaimer: Do not assume I am right, do your on research....