what is residual entropy?

Asked by Aashna Anith Kumar | 21st Feb, 2014, 12:29: PM

Expert Answer:

Residual entropy is the difference in entropy between a non-equilibrium state and crystal state of a substance close to absolute zero.

In other words,

The entropy possessed by a substance even at absolute zero is known as residual entropy.

Consider a crystal made up of AB molecule where A and B are similar atoms which has very small dipole moment. These molecules can adopt different orientations such as  -ABABAB-
or  -ABBAAAB-  at random. This arrangements or any other such arrangement have very little difference in energy. Thus, they have some disorder even at absolute zero, which is known as residual entropy.
This type of entropy is commonly seen in carbon dioxide.

Answered by  | 21st Feb, 2014, 12:43: PM

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