Question

What is residual entropy?

Answer 1

Entropy is an extensive property in the thermodynamics. The word residual entropy is used to describe the entropy at zero kelvin of a glass or plastic crystal which is referred to the crystal state.

Complete step by step answer: Residual entropy can be defined as the difference in entropy between a non – equilibrium state and crystal state of a substance that is close to absolute zero. The term absolute zero can be said as it is the lowest limit of the thermodynamic temperature scale. Residual entropy can also define as the entropy that is possessed by a substance even at absolute zero. The most common non equilibrium state observed is vitreous state, glass. Another example is carbon monoxide. It has a low dipole moment. Amorphous solid also comes under the list of examples. The residual entropy is related to the third law of thermodynamics. The third law of thermodynamics states that the entropy of a system approaches a constant value as its temperature approaches zero. That constant temperature can be said as the residual entropy.

Additional Information: Residual entropy is independent of temperature. Entropy can be expressed with the unit J/K or Joule / Kelvin. The entropy of a system at absolute zero can be said as typically zero.

Note: Residual entropy is different from thermal entropy. Thermal entropy can be defined as the entropy due to uncertainty in motion of molecules and vanishes at absolute zero. Thermal entropy is dependent on the temperature. The residual entropy of any substance can be said as the difference between the actual entropy and the ideal entropy.