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This was a question that was asked to me in my recent test.

I said that entropy will decrease as a hard boiled egg has molecules in a more organised way than an un-boiled egg, but I was marked wrong with a remark that entropy will increase because the proteins and other molecules are decomposed into simpler substances due to heat.

I did ask why I was not correct but what I got was the same explanation along with the decomposition reactions.

I don't feel this explanation is satisfying.


E.g. : - does not that makes 10 objects on a table organised properly have more entropy than 5 objects thrown anywhere on the table?

The definition of entropy is the measure of disorder in the system. So clearly in my above example the 10 objects are more organised and thus less disordered than the 5 objects in the second case and same can be said for the main question.


Can somebody please explain to me why a hard-boiled egg has more entropy than an un-boiled egg (I like if the explanation has some math) ?

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  • $\begingroup$ See similar question answered in Physics.SE here. $\endgroup$ – Don_S Jan 15 '17 at 7:47
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Here is an explanation I found on the internet that works for me:

The protein in egg whites is albumen, which is tightly folded in an uncooked egg. The balls will slide past each other, so it is a liquid. The entropy is low because of the precise folding.

After cooking, the protein molecules are unfolded and tangled, forming a solid. The entropy of the egg whites is actually higher.

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  • $\begingroup$ But why it is higher ? $\endgroup$ – A---B Jan 14 '17 at 20:31
  • $\begingroup$ Are you familiar with the term configurational entropy? $\endgroup$ – Chet Miller Jan 15 '17 at 1:52
  • $\begingroup$ Yes after reading en.wikipedia.org/wiki/Configuration_entropy . $\endgroup$ – A---B Jan 15 '17 at 8:17
  • $\begingroup$ But then does not that mean more things = more entropy regardless of how things are organised ? $\endgroup$ – A---B Jan 15 '17 at 8:29
  • $\begingroup$ It means that the polymer chains have more quantum states readily available to them in the final state than in the initial, well-organized, folded configuration. $\endgroup$ – Chet Miller Jan 15 '17 at 12:43
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I’ve come across several claims that a (hard) boiled egg has greater entropy than an unboiled egg. None of them cite any peer-reviewed research to back up their claim. While it is possible that entropy increases when you boil an egg, it is also possible that it does not. It is even possible that it stays the same.

I did my own literature search to see if I could find any publication that answered the question. What I found left the question very much up in the air. So I contacted Greg Weiss, a scientist who has done research on a related topic: ‘unboiling’ an egg. Dr. Weiss was kind enough to discuss the topic with me via email.


tl:dr

Whether a hard-boiled egg has greater entropy all boils down to the question of how structured are the assemblies found in aggregated ovalbumin. Furthermore, we can't just consider the assemblies found in the ovalbumin aggregate since we're talking about assemblies composed of all the types of protein in the overall albumen. (BTW, it's important to note that heated egg white doesn't just form any type of aggregate, it forms a gel, which presumably implies additional structure.)

For those who are interested in the details, here is the full email thread.

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