Engineers Out to Thaw the Mysteries of Ice (8/10/2008)
The Third Law of Thermodynamics is on the minds of John Cumings, assistant professor of materials science and engineering at the University of Maryland's A. James Clark School of Engineering, and his research group as they examine the crystal lattice structure of ice and seek to define exactly what happens when it freezes.
"Developing an accurate model of ice would help architects, civil engineers, and environmental engineers understand what happens to structures and systems exposed to freezing conditions," Cumings said. "It could also help us understand and better predict the movement of glaciers."
Understanding the freezing process is not as straightforward as it may seem. The team had to develop a type of pseudo-ice, rather than using real ice, in order to do it.
Despite being one of the most abundant materials on Earth, water, particularly how it freezes, is not completely understood. Most people learn that as temperatures fall, water molecules move more slowly, and that at temperatures below 32F/0C, they lock into position, creating a solid-ice. What's going on at a molecular level, says Cumings, is far more complicated and problematic. For one thing, it seems to be in conflict with a fundamental law of physics.
The Third Law of Thermodynamics states that as the temperature of a pure substance moves toward absolute zero (the mathematically lowest temperature possible) its entropy, or the disorderly behavior of its molecules, also approaches zero. The molecules should line up in an orderly fashion.
Ice seems to be the exception to that rule. While the oxygen atoms in ice freeze into an ordered crystalline structure, its hydrogen atoms do not.
"The hydrogen atoms stop moving," Cumings explains, "but they just stop where they happen to lie, in different configurations throughout the crystal with no correlation between them, and no single one lowers the energy enough to take over and reduce the entropy to zero."
So is the Third Law truly a law, or more of a guideline?
"It's a big fundamental question," says Cumings. "If there's an exception, it's a rule of thumb."
Violation of the 3rd Law of Thermodynamics
Posted 10 August 2008 - 09:40 AM
Posted 10 August 2008 - 12:09 PM
Posted 10 August 2008 - 12:26 PM
Posted 10 August 2008 - 01:02 PM
Because most of us believe that 3rd of thermodynamics always holds which is not true.
Be careful with your wording. The press release makes it clear that this research is not conclusive.
Materials that violated the Third Law as originally written were found in the 1930s, mainly non-crystalline substances such as glasses and polymers. The Third Law was rewritten to say that all pure crystalline materials' entropy moves toward zero as their temperatures move toward absolute zero. Ice is crystalline-but it seems only its oxygen atoms obey the Law. Over extremely long periods of time and at extremely low temperatures, however, ice may fully order itself, but this is something scientists have yet to prove.
Posted 10 August 2008 - 02:10 PM
Because most of us believe that 3rd of thermodynamics always holds which is not true. Do you have any questions?
From our rules:
"Do not post links to other sites as proof of your claims without commenting what the relevant sites say and why they are important to the current discussion."
So my point was that I want to here *why* you are posting it and what *your* opinion on the content is. That's all.
Posted 10 August 2008 - 11:21 PM
Do you think Dark Matter exists ? If yes then you are a believer.
Do you think that creation of periodic table has been explained ? If yes you are a believer.
Do you think Third Law of thermodynamics is a law ?If yes you are a believer.
The paper clearly says that as the temperature is lowered the ice doesnt set itself in the order.. that is what they are saying .. I am not... They are doubting the third law of thermodynamics which is right in my opinion also..
Try to explain which theory of kinetic energy can predict the sudden transition of solid into gas or vice versa... Do you think linear probability holds in such cases ? Third law of theormodynamics is only an approximation to the true nature of things and we should expect more and more substances to exhibit anomaly in the orderliness at lower temperature because the linear probability is no more applicable there. There are real forces at this close distances.
Anyways I not going to post anything which titillates the mind.Closed skepticism is very boring... good luck.
Posted 11 August 2008 - 02:25 PM
This is, in fact, not a violation at all of the third law which is properly stated:
If the entropy of each element in some (perfect) crystalline state be taken as zero at the absolute zero of temperature, every substance has a finite positive entropy; but at the absolute zero of temperature the entropy may become zero, and does so become in the case of perfect crystalline substances.
where glass, carbon monoxide and ice water are not perfectly crystalline structures and will therefore deviate from the law as expected.
Posted 11 August 2008 - 04:40 PM
All the affects are due to hydrogen bonding. The current theory of hydrogen bonding is not yet complete. It is not the third law of thermodynamics that is the problem. We found anomaly 65. The hydrogen has it own agenda, as does oxygen. In ice, the oxygen finally gives up, but the hydrogen is still putting up a fight. The system energy is minimized, but the potential of the hydrogen is not. This is reflected in free energy affect.
I have done this analogy elsewhere, but it is applicable here. Picture little brother (H) and big brother (O). They have an X-box but only one game controller. Because big brother is stronger he hogs the game. This situation may be the minimum system energy (minimum arguing, fighting, or pain) but it doesn't mean little brother is happy. He will not be able to sit still just because this is minimum system energy.
Posted 12 August 2008 - 12:53 AM
Oxygen drags the Hydrogen to Lowest System Energy but there are several routes to less and stable energy... Some pathways are actually at higher energy levels than the other but are equally stable... Hence we find that lowering of temperature doesnt always lead to minimum system energy.
Even the water molecules(not ice) have more than 3 structures. Ice have more than 15 .
All the structures are found at the same temperature...
Because all those structures are stable but they are not at same energy levels.
No compound(not element) is exactly symmetric therefore the 3rd law of thermodynamics does not apply to compounds.