Correct statement of 2nd law of thermodynamics?

In summary, the 2nd law of Thermodynamics states that in a closed system, total entropy never decreases and energy disperses, leading to a decrease in energy quality. This can be seen in the example of a hot coffee cooling down, as the decrease in energy quants leads to a decrease in entropy. This is a consequence of the law, which can also be mathematically stated as the number of possible arrangements in a system always increasing.
  • #1
Karagoz
Thermodynamics is stated in different ways. E.g.
In isolated systems entropy never decreases
Heat never spontaneously pass from colder to warmer body
Total energy quality decreases in all processes.
Energy disperses

But what is it exactly? What is the correct description of the 2nd law of themodynamics?
 
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  • #2
Karagoz said:
Thermodynamics is stated in different ways. E.g.
In isolated systems entropy never decreases
Heat never spontaneously pass from colder to warmer body
Total energy quality decreases in all processes.
Energy disperses

But what is it exactly? What is the correct description of the 2nd law of themodynamics?
Yes.
 
  • #3
Karagoz said:
In isolated systems entropy never decreases
Heat never spontaneously pass from colder to warmer body

Those two statements are logically equivalent. (That is, if you assume either one as a premise you can show that the other follows as a consequence.)

They are each statements of the 2nd Law. There is no way to say that either one is more or less correct than the other. And there are several other logically equivalent statements that are also equally correct statements of the 2nd Law.

These, on the other hand, seem more descriptive. They are perhaps consequences of the 2nd Law? But I wouldn't refer to them as statements of the 2nd Law.

Total energy quality decreases in all processes.
Energy disperses
 
  • #4
Would you like to see a mathematical statement of the 2nd Law of Thermodynamics?
 
  • #5
Mister T said:
Those two statements are logically equivalent. (That is, if you assume either one as a premise you can show that the other follows as a consequence.)

They are each statements of the 2nd Law. There is no way to say that either one is more or less correct than the other. And there are several other logically equivalent statements that are also equally correct statements of the 2nd Law.

These, on the other hand, seem more descriptive. They are perhaps consequences of the 2nd Law? But I wouldn't refer to them as statements of the 2nd Law.

2nd law of Thermodynamics says that total entropy never decreases in a closed system (in the universe).

In this link entropy is explained as "nr of possible arrangements": https://aatishb.com/entropy/
If you take a quick look at the link, according to the link above, more energy quants in a body can have more nr. of possible arrangements. Less energy quants in a body can have less nr. of possible arrangements.
Then that means any system that's cooling down (e.g. hot coffee cooling down) has a decreasing entropy, because the systems' energy quants decreases?
 
  • #6
Karagoz said:
decreasing entropy, because the systems' energy quants decreases?
... plus the "quants" increasing in the reservoir given up by the "coffee cooling." At least as much for a "reversible" process, zero net change, and for any "real process" occurring in less than infinite time, a greater than zero change.
 

Related to Correct statement of 2nd law of thermodynamics?

1. What is the second law of thermodynamics?

The second law of thermodynamics states that in any spontaneous process, the total entropy of the universe will always increase. This means that the overall disorder or randomness of the universe will always tend to increase over time.

2. How is the second law of thermodynamics related to energy?

The second law of thermodynamics is related to energy because it states that in any energy transformation or transfer, some energy will always be lost as heat. This loss of energy is inevitable and contributes to the overall increase in entropy in the universe.

3. Can the second law of thermodynamics be violated?

No, the second law of thermodynamics is a fundamental law of nature and cannot be violated. While it may seem like some processes go against the law, they are actually in accordance with it when considering the entire system.

4. How does the second law of thermodynamics apply to living organisms?

The second law of thermodynamics applies to living organisms because they also participate in energy transformations and transfers. In order to maintain their own organization and decrease their own entropy, living organisms must constantly take in energy from their surroundings and release it as heat.

5. Can entropy be decreased in a closed system?

No, the second law of thermodynamics states that the total entropy of a closed system will always increase. This means that even if some parts of the system decrease in entropy, there will be an overall increase in the system's entropy.

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