Question

How can the entropy of a pure solid to be zero?

Answer 1

Well, according to the third law of thermodynamics...........

Explanation:

The third law of thermodynamics states that `"the entropy of a perfect crystal at 0 Kelvin is ZERO"`......

And such a crystal (and this is very much an abstract concept) has only the one possibility of arrangement and thus the statistical probability for disorder, the entropy, is ZERO.

The existence of the third law allows us to deal with absolute entropies i.e. `S^@` under standard conditions, rather than parallel values of `DeltaH^@`, where only enthalpy changes can be specified.