When a system can only be prepared in one way

[Katherine Grillo 1B]

What does it mean that a system can only be prepared in one way? And why does that mean S=0?

[Chem_Mod]

This is referring to when there is only one state/position available to the molecule(s). If there is only 1 position, then W (degeneracy)= 1^{number of molecules}, and 1 raised to any power is still 1, then the ln(1)=0 so if S= k_Bln(W) then S=0. This tells us that the molecule or molecules do not possess any residual, or positional, entropy.

[Christopher Anisi 2K]

That means that the system can only be oriented in one way meaning that it only has one energy state or degeneracy value of 1. And when utilizing S=KBlnW assuming there is only residual energy involved that would give you an entropy value of 0.