1 / 10

The Second Law of Thermodynamics

kalonice
Download Presentation

The Second Law of Thermodynamics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. The Second Law of Thermodynamics

    2. Coin Flip Problem You have two pennies:

    3. What combinations of these pair of pennies are possible?

    4. The likely state of this system will be one Head and one Tail. Now imagine having 3 pennies. What are the combinations? 1 HHH =N!/(n!(N-n)! 3 HTT N = # of pennies 3 HHT n = # of heads, etc. 1 TTT

    5. Extend this analysis to 50 pennies. The chance that you could get 50 heads or 50 tails is vanishingly small. The most likely combination will be those with the most variations.

    6. Natural processes proceed toward those states that have the greatest number of chances to get equivalent outcomes. For four pennies there is 6 ways to get two heads and two tails, but only one way to get 4 heads. For 50 pennies there are 12.6 Million different combinations 25 head or 25 tails.

    7. Entropy A measure of disorder. Natural processes proceed to increasing disorder. Disorder means lack of predictability. Those states that have the most order are the least likely for the system to end up in.

    8. Question? Would conservation of energy allow the process whereby a cup of hot water sitting on your kitchen table would suddenly freeze? A. Yes B. No

    9. Why doesnt it happen? Because the frozen liquid represents a more ordered state than the liquid state. There are many more probable states available for the system to be in and so thats where it will go.

    10. Lord Kelvin used Carnots concepts to analyze the heat flow into and out of Carnots engine. He discovered that the ratio of Q/T was constant and called this state function entropy, S. The change in entropy became a measure of whether a reaction was spontaneous or not, DS > 0 meant spontaneous.

More Related