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Topic: Osmosis-diffusion  (Read 6492 times)

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Offline 2810713

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Osmosis-diffusion
« on: March 18, 2005, 01:32:13 PM »
 Osmosis and diffusion [mostly encountered in biological systems] increase entropy and thus are  feasible.
But, how do they increase entropy ? ? ?

please help...

thanx

hrushikesh

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Re:Osmosis-diffusion
« Reply #1 on: March 19, 2005, 11:58:44 AM »
First off, nice name. Try playing it in lottery!  :D

There are two things that energy can do. One is to perform work, the other is to dissipate into energy states. The entropy is the portion of energy that is absorbed by energy states such as molecular translations, vibration, and rotation.
Thermodynamically, S = q(rev)/T = [E - w(rev)]/T. So, less work means more energy can be "wasted" as entropy. Of course, nature is lazy and prefers to maximize entropy.

In osmosis and diffusion, the stock answer is that the increased disorder of the final state leads to an increase in entropy. But what does disorder have to do with energy?
It can be shown by statistical mechanics that  the number of energy states in mixed systems increases due to the increased number of distinguishable arrangements of particles (a translational phenomenon). The increased availability of these energy microstates allows available energy to access them as entropy.
« Last Edit: March 19, 2005, 12:23:57 PM by Demotivator »

Offline Borek

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Re:Osmosis-diffusion
« Reply #2 on: March 20, 2005, 05:30:10 AM »
Osmosis and diffusion [mostly encountered in biological systems] increase entropy and thus are  feasible.
But, how do they increase entropy ? ? ?

Adding some more descriptive picture to the Demotivators answer:

Entropy is a measurement of the lack of order in the system. Imagine a kids room with some toys stacked on the floor in one place. There is some order. Now enter the kids for half an hour and check the room after. Toys are eveywhere - not stacked in one place. There is no order. Entropy rised. Now, if you have a glass of water and you put a drop of concentrated salt into it you have the same situation as with the room with stacked toys - there is some order. Diffusion works like kids - it distributes the salt uniformly in the solution (room) - order decreases, entropy rises.
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Offline 2810713

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Re:Osmosis-diffusion
« Reply #3 on: March 22, 2005, 04:10:15 AM »
 Thanks, it helped  me . reviosion of concepts provoked
a series of thoughts and that helped me get it cleared.
The example of kids and toys was really good. But, I could not understant how did you explain the concept of entropy using [E - w(rev)]/T , because this work is reversible so, it is not practical. Also, how to get q(rev) ? ? ? This is still not clear, should i start a new post ? ? ?

My user name is good but myname is hrushikesh [see below the message]

thanks

hrushikesh

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