Standard molar entropy

In chemistry, the standard molar entropy is the entropy content of one mole of substance under a standard state (not STP). The standard molar entropy is usually given the symbol S°, and as units of joules per mole kelvin (J mol−1 K−1). Unlike standard enthalpies of formation, the value of S° is absolute. That is, an element in its standard state has a definite, nonzero value of S at room temperature. The entropy of a pure crystalline structure can be 0 J mol−1 K−1 only at 0 K, according to the third law of thermodynamics. However, this presupposes that the material forms a 'perfect crystal' without any frozen in entropy (defects, dislocations), which is never completely true because crystals always grow at a finite temperature. However this residual entropy is often quite negligible.

Standard molar entropy

In chemistry, the standard molar entropy is the entropy content of one mole of substance under a standard state (not STP). The standard molar entropy is usually given the symbol S°, and as units of joules per mole kelvin (J mol−1 K−1). Unlike standard enthalpies of formation, the value of S° is absolute. That is, an element in its standard state has a definite, nonzero value of S at room temperature. The entropy of a pure crystalline structure can be 0 J mol−1 K−1 only at 0 K, according to the third law of thermodynamics. However, this presupposes that the material forms a 'perfect crystal' without any frozen in entropy (defects, dislocations), which is never completely true because crystals always grow at a finite temperature. However this residual entropy is often quite negligible.