Concept of molar entropy

[Sam Joslyn 1G]

When one substance has a lower molar entropy than another, what exactly does that mean conceptually? Does it need less heat than the other substance to become more disordered?

[Camille Marangi 2E]

Conceptually, a lower molar entropy substance is just more ordered than another substance in comparison. For example H20 (s) has a lower molar entropy than say H20 (g). The particles in ice are more tightly and rigidly held together than in water vapor. You can also see this in the Boltzmann equation for entropy which is S=KblnW.

[A De Castro 14B 2H]

When one substance has a lower molar entropy than another, it means that substance is comparatively more ordered (less disorder). This further indicates that more heat is needed to make it more disordered than the other substance. For example, ice (solid H₂O) has lower molar entropy than water (liquid H₂O), so ice needs more heat than water to turn it into steam (gaseous H₂O).