## Machida one year ago Show me the second law of thermodynamics and example to apply it.

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1. Machida

@goformit100

2. goformit100

Sure

3. Machida

lets discuss abt it

4. RANE

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/seclaw.html this explains wht it is and also provides examples to explain the concept

5. Machida

@RANE, I wanna discuss it here :D cmooon

6. Machida

7. goformit100

ya but she wants the explanation. I have many llinks like that ...

8. Machida

LOOOL I give up if you just link me of that lul @goformit100

9. goformit100

ok lets start... yu begin first.

10. Machida

btw i just wnna make this subject ALIVE :D

11. Machida

@goformit100 Carnot?

12. goformit100

ok

13. goformit100

ya do you know 2nd law is defined in about 10 ways by different scientists

14. Machida

nah, tell me 10 :3

15. Machida

16. goformit100

ok

17. goformit100

All the spontaneous process are irreversible in nature.

18. Machida

-_-

19. Machida

Why thermodynamics on chem section, not in phys section?

20. goformit100

21. Machida

lol i have small eyes (aka squinty)

22. goformit100

That can only be answered by Miss @Preetha

23. Machida

woka woka. im afraid now.

24. joemc

In chemistry, this is where entropy is usually introduced.....

25. Machida

@joemc . you mean like carnot?

26. Machida

Oh I see.

27. joemc

The first law introduces internal energy, U. Second law introduces entropy, S

28. goformit100

Entropy of the universe always keeps on increasing

29. joemc

Carnot is brought in here, at least the Carnot efficiency.

30. Machida

Congratss for 50 SS. :3 I give you amed for it :)) you're awesome ★░░░░░░░░░░░████░░░░░░░░░░░░░░░░░░░░★ ★░░░░░░░░░███░██░░░░░░░░░░░░░░░░░░░░★ ★░░░░░░░░░██░░░█░░░░░░░░░░░░░░░░░░░░★ ★░░░░░░░░░██░░░██░░░░░░░░░░░░░░░░░░░★ ★░░░░░░░░░░██░░░███░░░░░░░░░░░░░░░░░★ ★░░░░░░░░░░░██░░░░██░░░░░░░░░░░░░░░░★ ★░░░░░░░░░░░██░░░░░███░░░░░░░░░░░░░░★ ★░░░░░░░░░░░░██░░░░░░██░░░░░░░░░░░░░★ ★░░░░░░░███████░░░░░░░██░░░░░░░░░░░░★ ★░░░░█████░░░░░░░░░░░░░░███░██░░░░░░★ ★░░░██░░░░░████░░░░░░░░░░██████░░░░░★ ★░░░██░░████░░███░░░░░░░░░░░░░██░░░░★ ★░░░██░░░░░░░░███░░░░░░░░░░░░░██░░░░★ ★░░░░██████████░███░░░░░░░░░░░██░░░░★ ★░░░░██░░░░░░░░████░░░░░░░░░░░██░░░░★ ★░░░░███████████░░██░░░░░░░░░░██░░░░★ ★░░░░░░██░░░░░░░████░░░░░██████░░░░░★ ★░░░░░░██████████░██░░░░███░██░░░░░░★ ★░░░░░░░░░██░░░░░████░███░░░░░░░░░░░★ ★░░░░░░░░░█████████████░░░░░░░░░░░░░★ ★░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░★ @joemc BACK TO CHEM

31. joemc

But, a second law problem in chemisty could be something like.... Calculate the entropy change when Neon, at 25 C and 1.00 atm in a 500ml container i allowed to expand to 1 L and is simutaneously heated to 100 C

32. goformit100

@Machida you care so much of others. you are so kind to the good ones.

33. Machida

@joemc . wait, whats for exactly that law? chem or phys first? Ya, I dont think abt it before. :o

34. Machida

@goformit100 because caring each other for intelligence is awesome :)

35. joemc

You would calculate the entropy of the system at each temperature and then calculate the difference.... Equation to follow....

36. Machida

wow, im too stupid of that :/

37. joemc

At constant pressure: $S(T_F) = S(T_i) + \int\limits_{i}^{f} (\frac{ C_P }{ T })dT$ At constant volume: $S(T_F) = S(T_i) + \int\limits\limits_{i}^{f} (\frac{ C_V }{ T })dT$

38. joemc

So, you need to break the problem down into two steps and figure the difference of each change. One part is isothermal, the other adiabatic.

39. joemc

What types of problems are you looking for...the Gibbs function also is part of this and probably more approachable.

40. Machida

Well, let me do it tomorrow. i need to understanding that materials again. :D btw thanks a lot for make me thought abt it

41. joemc

OK, good night!

42. Machida

Good noon :D

43. Frostbite

I always like to give the following image of the 2. law: Consider a ball (our system) bouncing of the floor (the surroundings). The ball does not rise as high after each bounce because there are inelastic losses in the materials of the ball and floor. The kinetic energy of the ball’s overall motion is spread out into the energy of thermal motion of its particles and those of the floor that it hits. The direction of spontaneous change is towards a state in which the ball is at rest with all its energy dispersed as the disorderly thermal motion of molecules in the air and spread over the atoms of the virtually infinite floor. So what are we trying to say: We look for the direction of change that leads to the random dispersal of the total energy of the isolated system. Leading to our understanding of the second law of thermodynamics: The entropy of an isolated system increases in the course of a spontaneous change: ∆S_total > 0